Category: Articles

Earth Air Fire and Water
The Pharmageddon Herbal
Ivor Hughes
Chapter 10C continues

The Plant Juices10.40
The ‘succi’ or expressed plant juices still find a place in some homoeopathic pharmacopoeias but for some very good reasons are no longer official in the US and British Pharmacopoeias. The succi had long been popular in Continental Europe from whence they were introduced to Britain by a man called Squire, via ‘Squires Dispensatory’ which was eventually incorporated into ‘Martindale’s’ extra pharmacopoeia.

At that time such publications were widely consulted by the medical profession for information on drugs not contained in the Pharmacopoeia, and enjoyed a semi-official status. In the US they were admitted to the pharmacopoeia in 1870 and then subsequently phased out.

In Britain ‘Squire’ had introduced them via his Dispensatory in 1835 from where they became official. However by 1914 only three succi remained and they weredeleted entirely by the 6^th edition of the BP in 1932.

The supply of fresh plants for pharmaceutical purposes was attended by considerable difficulties, also many plants were not available by reason of geographical distance, and also by nature of the plant or parts required, some containing insufficient sap to render the operation feasible.

The recommendations were, that the plant should be operated upon immediately after collection. If the plants were some hours old after collection they were to have their stalks placed in water for some 12 to 18 hours to refresh them. Any plants that were still wilted were to be discarded.

Even this procedure introduced the problem of ‘engorgement’ which considerably increased the water content of the plant thereby rendering the menstruum strength unreliable if it was to be used for preservation purposes. The recommended procedure was as follows;

A. Chop the plants and contuse them in a stone mortar until reduced to a pulpy consistency. If this proves difficult add a little water to assist the process.

B. The pulp is then introduced to a linen bag and the whole subjected to pressure.

C. The expressed juice is then gently heated to a temperature not exceeding 24°C to coagulate the albumen which would otherwise cause the juice to putrefy.

D. The juice is then filtered to remove any extraneous matter. It is then reduced by evaporation to the consistency of syrup and preserved with ether or chloroform. Alternatively without evaporation the juice is preserved by the addition of an equal part of alcohol.

This procedure of obtaining the plant constituents is totally unsatisfactory on the following grounds;

1. It is not possible to remove all the liquids by pressure

2. The juice is composed mainly of water, upwards of 98%; considerable amounts of non water soluble constituents are retained in the marc.

3. Any non soluble constituents in the solution are removed by filtration. The liquid obtained is incomplete and most uncertain in its action.

For all of the reasons given the succi were abandoned. The fact that some are still included in homoeopathic pharmacopeias owes more to convention of the sacred cow type than it does to good pharmaceutical practice.

Tinctures from Fresh Plants 10.41
Fresh plant tinctures may be considered animprovement on that of that succi however there are attendant problems that can only be resolved by resorting to very lengthy procedures

Some homoeopathic pharmacopeias have attempted to address the matter but no method can be said to be more than a compromise solution, given the number of variables, not to mention species involved.

Tinctures and extracts prepared from dried plants represent the virtues of the plant in a concentrated form. The water content of fresh plantsis subject to numerous variables, e.g. season or engorgement from wet weather etc.

Assume for the sake of an example that the average water content of fresh plant material is 75% and that of dried plant material to be 7.5%.

We may see that weight for weight 1g dried equals 10g fresh, therefore if an extraction process calls for a 1:4 ratio and we extracted 1kg of dried material in 4 litre of menstruum we would need to use 10kg of fresh to achieve an extraction of similar strength in terms of the plant’s soluble constituents.

The volume of 10kg of chopped plant is considerably greater than 4 litres of liquid. Remember the plant material cannot be pulverized because of the hydrolysis problem.

Even if the plant was reduced to a slurry we will end up with around 10 litres of liquid after filtration and we have completely destroyed the integrity of the menstruum, so the extraction would be incomplete.

Because of the volume problem, the ratio adopted for fresh material is 1:2, i.e., 1kg in 2 litre, therefore in comparison with the dried material the equivalent ratio is 1:20, i.e. 100g of dried material is the equivalent of 1kg fresh.Tinctures of fresh plants are prepared by the maceration process described in Section 10.23. We are of course still left with the problem of the integrity of the menstruum.

Homoeopathic pharmacists have devised various methods to overcome the problems. The methods are lengthy and imprecise. The methods include such procedures as determination of dry residuecontent of succi. Loss of weight on drying of fresh plants. Finally the integrity of the menstruum problem is tackled by using 86% alcohol to produce afinal strength of circa 43% by volume.

Considerable precipitation occurs. Attempts to bring about a partial solution of the precipitated constituents is not very successful which leaves a question mark over the efficacy of the preparation.

As previously explained, tinctures offresh plants are the equivalent of 1:20. A homoeopathic mother tincture is 1:10 therefore when producing the dilutions from them on the appropriate scale we proceed as follows;

1. The 1^st decimal potency 1x = 2 parts fresh plant tincture in 8 parts menstruum of appropriate strength and succussed.

2. The 2^nd decimal potency 2x = 1 part of 1x in 9 parts menstruum and succussed.

1. The 1^st Centesimal potency 1C = 2 parts fresh plant tincture in 98 parts menstruum and succussed.

2. The 2^nd Centesimal potency 2C = 1 part of 1C in 99 parts of menstruum and succussed.

This type of preparation is not recommended. To avoid problems always use dehydrated plant material. If the mother tincture is made from dried plant material the 1^st dilution is always 1 part in 10 or 1 part in 100 as the case may be.

The Extracts (Extracta) 10.42
The extracts are the most important class of botanic preparations. They represent the base substance from which all other classes are derived. There are three distinct types;

1. The fluid extracts. As the name implies these are liquids containing the soluble extractive matter of a plant. They are so prepared that 1ml of fluid represents 1g of the standard air dried drug. The ratio is 1:1. From them may be prepared all other official concentrations and tinctures by dilution with a matching solvent.

2. The Soft Extracts. The soft extracts may be syrupy or pasty in consistence. They are prepared from fluid extracts by reduction of the menstruum by evaporation or distillation under low pressure. The soft extracts are used as the basis for creams, ointments, suppositories, lozenges and pills.

3. The Dry Extracts. The dry extracts may be in the form of powder, granules or scales. They are prepared from the soft extracts by means of a suitable drying process. Care must be taken not to use excessive heat lest damage occur. They are hygroscopic so must be kept in sealed containers in a cool dry place. The major use is in the preparation of tablets or capsules.

The fluid extracts are obtained by the percolation of the drug with an appropriate solvent and are superior to those preparations obtained by maceration in that a virtually complete extraction is achieved when the operation is correctly performed.

The Percolation Method 10.43
Percolation is a method of extractionachieved by the downward displacement of soluble extractive by a suitable solvent through a suitably comminuted drug plant. The process is a combination of maceration and percolation and is sometimes referred to as a process of ‘Macero-Percolation’. Not all plant drugs are suitable for the process. There are 7 distinct operations involved, they are in order of operation;

1. Comminution.The principles of size reduction are covered in paragraph 10 -16. Remember if the particles are too fine a solid cake may occur, this will effect the downward flow of menstruum and will most certainly lead to the formation of ‘dry pockets’ within the body of the material which will escape extraction. It the material is too coarse then interstices are formed through which there is a speedy percolation of menstruum which produces an incomplete extraction and will require excessive volumes of menstruum to exhaust the marc.

2. Imbibition. The word is derived from the Latin meaning ‘to drink in’. The comminuted drug thoroughly moistened with a portion of the menstruum. This is best done in a lidded container of a suitable size. The moistened drug is allowed to stand for a period of four hours to allow the drug to imbibe the menstruum and thereby swell to its maximum capacity. The container used should be large enough to accommodate the expansion of the drug.

3. Packing.On completion of imbibition the drug should be passed through a number 10 sieve to break up any lumps that may have formed. The drug is then transferred to the percolation vessel in portions. Each portion should be firmly packed but not so firmly that liquid is forced from the drug but sufficient to exclude any air pockets.

4. Maceration. Open the stop cock on the bottom of the percolator and pour in the menstruum in portions and allow to percolate through the packed drug. If the menstruum drips through the stop cock in less than 10 minutes, the drug is too loosely packed. If the first drop takes 25 minutes or more then the drug is too tightly packed. If all is well, then close the stop cock and pour in sufficient menstruum to leave a layer 1 or 2 cm deep over the drug. Cover the percolator and leave to macerate for 48 hours in a warm dark place at a temperature not exceeding 25°C.

5. Percolation. On completion of maceration the percolation procedure is commenced. Slowly open the stop cock and adjust the flow of saturated menstruum to 10ml per minute for the first 10% of the total menstruum, thereafter adjust the flow to10 drops per minute.

6. Adjustment.When the first 85% of the percolate has been collected, the receiver is changed and the first portion is reserved. The percolation into the fresh receiver is continued until the drug is exhausted. The marc is pressed and the expressed menstruum is mixed with the contents of the second receiver. That fluid is then reduced to a soft extract and then dissolved into the reserved 85% in the first receiver. The total is then adjusted to volume with a matching strength menstruum.

7. Clarification.The extract is sealed and allowed to stand in a cool dark place for a minimum of 48 hours (a week if times allow) after which it is filtered to remove any sedimentation and may then be considered ready for use. Correctly prepared and correctly stored the product will have a shelf life of 10 years.

Percolation Apparatus 10.44
Whenever possible such apparatus as percolators should be made of glass for ease of cleaning and the ability to make visual progress check. The percolator may be purpose built or obtained from a laboratory supply house, or you may construct your own. The general scheme may be as per the following diagram.

The Percolator.Figure 10.44A

The percolator should be cylindrical and if possible tapered, with a lid to fit to prevent evaporation of a volatile menstruum.

The packed drug is covered with a filter paper and a layer of clean sand to maintain the packing without disturbance and the cotton wool plug is to prevent the packed drug from being washed into the receiver.

Where possible the percolator and ancillary equipment should be of sufficient size to contain all of the menstruum plus the drug. If this is not possible then the bulk of the menstruum may be contained in a reservoir as follows;

The level of menstruum will be maintained at the neck of the bottle until it is empty, where upon it should be removed and replaced with the percolator lid.

To minimize loss of solvent by evaporation the opening of the receiver/collector should be kept as small as possible; a graduated flat bottomed boiling flask of a suitable size will serve the purpose well.

 

The Reservoir Figure 10.44B
There are subsidiary methods of percolation for example a system of re-percolation whereby the total drug to be extracted is divided into three parts; the ratio being 5, 3 and 2 respectively, that is, 500g, 300g, 200g = 1kg.

The total menstruum is passed through each part in succession. The method being similar to the ‘concentrated infusions’. The only benefit is that any subsequent evaporation is avoided.

In practice the procedure is lengthy and it is virtually impossible to extract the drug to exhaustion. Therefore, as a procedure it is not recommended. The following process is the recommended method which will meet most operational requirements and maintain the necessary standards.

The Reserve Percolate Method 10.45
The percolation method of drug extraction may obviously be used for the tinctures as well as the concentrated preparations.  Therefore, the volume of the menstruum needed to extract the drug to exhaustion will vary according to the drug/menstruum ratio applied. Also, the strength of the menstruum will vary depending on the material being operated on.

To arrive at an estimation of the volume of menstruum required proceed as follows;

For the purpose of example, let us suppose that we require 1000ml of a 1:4 tincture, i.e., 250gm of drug in 1 lt. From Paragraph 10.25 we will recall that 1gm of drug will hold around 1.5 times its own weight in menstruum when it is saturated; in addition an allowance of menstruum must be made for the Imbibition process. The following method for calculating the menstruum will in most cases be of reasonable accuracy.

Table10.45A. Tincture 1:4

It will be seen from the table that the more concentrated the extract the greater the volume of menstruum needed to complete the extraction. The procedure to be followed is as described in Section 10.43.5 of that paragraph it is stated that the percolation is to proceed at 10 drops per minute. If the volume of the extract required exceeds2 litres, the speed of percolation can be stepped up to 20 drops per minute, this is accounted for by the greater rate of displacement produced by the greater weight, of menstruum involved.

The first 85% of the required percolate is reserved, i.e., if 1000ml of extract is required then the first 850ml is placed to one side and stoppered to prevent evaporation or contamination. The percolation is then continued with a fresh receiving flask until the drug is exhausted.

For example in Table 10.45A, the 1:1 extract calls for 3000mlof menstruum. We collect and reserve the first 850ml leaving a balance of 2150ml for collection. It will be convenient to collect this in 2 or 3 receivers, in that way the progress of the extraction can be visually monitored. The collected menstruum will get progressively lighter in color as the amount of soluble extractive remaining in the drug declines with percolation.

When the percolate ceases to drip from the extractor, the marc is transferred to a linen or calico bag and subjected to pressure to express the remaining menstruum. In addition to the reserved percolate, there should now be just over 2 litres of weak extract which contains the remaining 15% of the total extract to be recovered, and added to the reserved percolate for adjustment to therequired 1000ml.

For the purpose of illustration, assume that the drug required a 70% alcohol menstruum to effect the extraction and that the starting strength of the dilutealcohol was 95%. A perusal of Table 9.33A shows that the 70% alcohol contains 40 volumes of water, i.e., every 100ml of 70% menstruum contains 60ml of alcohol and 40ml of water.

From this 2 litre of percolate wereserve 150ml and place it to one side, to be used to dissolve the soft extract recovered from theremaining 1850ml of percolate.

The extract is recovered by reduction of the menstruum eitherby evaporation or distillation under reduced pressure. Whichever method of recovery is chosen the temperature must not be allowed to exceed 55°C lest damage to the extractive ensue.

It may be supposed that it would be far easier tosimply reduce the 2 lt. of percolate to 150ml and add it to the reserve, however if we change the strength or composition of a menstruum, then precipitation will occur. In the reduction process the alcohol will be removed first, then followed by the reduction of water down to the required volume of 150ml.This is an aqueous percolate which if added to the 850ml of reserved percolate then aprecipitation of the whole would occur; that is the reason for the somewhat lengthier procedure employed.

Table 10.45B

The method of reduction by distillation underreduced pressure is favored over evaporation because the menstruum so recovered may be re-used and the temperature and duration of the process is considerably reduced. However if the menstruum is aqueous as it would be for an extract of malt or liquorice, then evaporation over a water bath will be found to be more convenient, given the larger quantities of substances involved. A flat bottomed evaporating pan facilitates the removal of the syrupy or pasty extracts.

The Soft and Dry Extracts 10.46
The soft and dry extracts are of great service in the preparation ofpills, tablets, capsules, ointments etc. or where the use of alcohol in a preparation is contra indicated. In such cases a portion of the extract may be dissolved in warm water as a fresh infusion or incorporated with the honey or syrup

The Soft Extracts 10.47
The soft extracts are syrupy or pasty in consistency. The alcohol has been removed and the water content reduced. Remember that spoilage organisms thrive in the presence of water therefore the water must be reduced to 5% if they are to be stored. Prepare them as follows.

1. Produce a fluid extract with the appropriate menstruum. When the drug has been exhausted all of the menstruum may be mixed, i.e., the reserve percolate method is not resorted to.

2. Fraction out the alcohol by distillation under reduced pressure. The alcohol recovered for Galenic preparations is reused after it has been rectified.For Spagyric or Homoeopathic work the recovered menstruum may only be employedfor the original specie used.

3. Transfer the remaining fluid to a water bath to effect removal of the bulk of water. The temperature of the water bath should not exceed 60°C and should preferably be maintained at 50°C. This is most important if hydrolysis or the Racemization (L and D isomers) of the extraction is to be avoided. The heat loss involved by transfer from the water to the evaporating pan is usually circa 5°C, therefore, temperature control is a must.

4. The evaporating pan should be as large and as shallow as possible. The larger the surface area of the extract which is exposed to the atmosphere the swifter the evaporation. The extract must be stirred on a regular basis to break up the film or skin which forms on the surface of the extract. If this is not done, the evaporation process is retarded. Racemization may also occur due to an overlong evaporation procedure. If the quantity of the extract involved is large then it may be divided into portions and evaporated separately. All portions must be operated on within 12 hours lest spoilage by micro organisms occur.

5. When it is judged that the extract is at the consistency required, take a small porcelain crucible and accurately weigh it. Take a small portion of the extract and transfer it to the crucible. Re-weigh the crucible and tare it, i.e., subtract the weight of the crucible to obtain the weight of the extract. Gently heat to reduce the extract to a dry state and allow to cool. Re-weigh and tare. The difference in weight between the liquid and dried extract is the amount of water it contains.

6. When the desired consistency is reached, the extract may then be transferred to sterile storage containers, tightly sealed and stored in a cool dark place. Shelf life is circa 12 weeks.

The Dry Extracts 10.48
When a fluid extract is reduced to a dry state by evaporation in the atmosphere, it is hygroscopic and tends to produce a dense intractable mass which is difficult to work with, dissolve or to store. Those problems may be circumvented by reducing the soft extract to 1 of 2 forms, i.e., scales or granules.

The Dry Scales 10.49
1. The syrupy soft extract is painted or very thinly spread with a spatula onto sheets of heat resistant glass or Pyrex ovenware. The extract is then dried in a cool oven at a temperature not exceeding 40°C. At no time should the extract be exposed to direct radiant heat or treated in a microwave oven lest irremediable damage occur.

The Granulated Extracts

Figure 10.49A
1.The syrupy warm extract is transferred to a strengthened Buchner filter flask which is suspended in a water bath.

2. The flask is attached to a vacuum pump or venturi tube The system is then sealed and the vacuum pump turned on and the pressure inside the flask quickly reduced. There will be a sudden evolution of water vapor causing the extract to balloon into a porous friable mass.

3. Slowly open the vacuum release cock and turn off the pump. Remove the flask from the water bath.

4. The friable mass may be dislodged from the Buchner flask by means of a glass stirring rod. Rub the mass through a 14 mesh sieve and store as for the dried scales.

5. The Buchner flask should not stand in the boiling water any longer than  three minutes  before the vacuum pump is turned on.

Supplementary Procedures 10.50
Some plant materials contain lipids, i.e., waxes, fats and oils. They are usually seeds or fruits, (essential oils are not lipids, except in rare instances). For example, oil seeds, they are not present in such quantity so as to materially effect the extraction procedure, however they will cause problems when attempting to produce a soft extract and will render a dry extract impossible due to the oily nature of the reduced extract. The procedure to remove the oil is called de-fatting. It is carried out as follows.

Table 10.50A

Continuous Hot Extraction 10.51
The extraction of a solute from a solid by means of a cold solvent is a slow process but it is a necessity if the integrity of the solute is to be maintained. However many routine analytic tasks performed in a laboratory are concerned with elemental constituents rather than the molecular structure. The need was for speedy delivery of small quantities of substances for routine analysis; this was achieved by the continuous hot percolation method.

The piece of equipment used is a standard to most laboratories and is known as the ‘Soxhlet Extractor’, named after a German agricultural chemist Franz von Soxhlet (1848 -1926).

Soxhlet ExtractorFigure 10.51A

(A)Reflux condenser
(B) Hot vapor tube
(C)Percolate return tube (by siphon)
(D) Soxhlet Extractor (Body)
(E) Extraction Thimble
(F) Boiling flask.

The path of the solvent is;

(F) – (B) – (A) – (D) – (E) – (C) – (F)

The hot solvent vapors pass from flask (F) and rise through tube (B) and condenses in (A). The lukewarm liquid then drips into thimble (E) where it percolates through the substance contained in the thimble. The percolate from (E) passes to (C) where it rises until its height matches that in (E) when it will automatically siphon back to (F).

So long as the boiling flask (F)is heated the process will be continuous; between 10 and 15 cycles, depending on the substance will be needed to exhaust it. The two major points here are,

 

1. The substance is extracted with lukewarm condensed solvent and not hot;

2. The soluble substance extracted, remains in the boiling flask and is subjected to the heat of the boiling solvent for in excess of 30 minutes.It will be clearly understood that such a process is too violent and destructive to be of use in extracting plant materials. However it is of major importance when preparing a Spagyric tincture or extract where it is used to extract the soluble salts from the extracted marc. The Spagyric method will be covered later in the text.

An Alternative Continuous Extraction Apparatus 10.52.
The Soxhlet apparatus is delicate and expensive if broken; it is prone , if the thimble is too tightly packed to leave a dry core of un-extracted material, so that the procedure would need to be repeated. Those problems may be avoided by using alternative extractors which are commercially available, e.g.,

Figure 10.52A
(A) Reflux Condenser

(B) Hot Vapor Tube

(C) Boiling Flask

(D) Body of Extractor

(E) Substance for extraction

(F) Sintered Glass Filter Plate

 

The path of the solvent is;

(C) – (B) – (A) – (D) – (E) – (F) – (C)

The alternative is relatively cheap and less prone to breakage. It has proven to be satisfactory when used in the Spagyric process. A 20 minute circulation will exhaust a calcined marc of its soluble salts.

 

The Essential or Volatile Oils 10.53
As a class of product the essential/volatile oils are commercially important and because of the large quantities of base material required to obtain a relatively small yield they are also expensive.

Table 10.53A Average Yields

Common Name.	Botanical Name.	% Yield.
Arnica Flowers	Arnica montana	0.04%
Basil Herb	Ocimum basilicum	0.04%
Chamomile Flowers	Matricaria chamomilla	0.50%
Hyssop Herb	Hyssopus officinalis	0.40%
Lavender Flowers	Lavandula vera	2.90%
Lemon Balm Herb	Melissa officinalis	0.10%
Peppermint Herb	Mentha piperita	0.30%
Rose Flowers	Rosa spp.	0.01%
Rosemary Herb	Rosmarinus officinalis	1.55%
Sage Herb	Salvia officinalis	1.40%
Tansy Herb	Tanacetum vulgare	0.15%
Violet Flowers	Viola odorata	0.03%
Wormwood Herb	Artemisia absinthium	0.35%

The oils are plant isolates are used for perfumery, flavoring and medicines. It must be emphasized that medicinally they are not the equivalent of the tinctures and extracts and only display a narrow band of a plant’sfull therapeutic spectrum. Taken internally they can be extremely toxic, to the point of fatality. Externally they are irritant/rubefacient and should not be used in the undiluted form, especially around the eyes or on mucous membrane.

Orthodox medicine employ them internally in dilute form asdigestives or carminatives and occasionally as inhalants where they are of great service due to their volatile nature and undoubted bactericidal properties. As a product they are used by a branch of complementary medicine called ‘Aromatherapy’ where the volatile oils are diluted in a fixed oil and applied externally.

Occurrence and Nature 10.54
The study of function and genesis of any constituent, in a living organism is problematic, and conclusions are constantly being revised. The essential oils are sometimes referred to as pseudo-lipids because like the oils and fats they are soluble in organic solvents, it is there that any similarity ends. The volatile oils have their genesis in the chlorophyllic soft tissue (parenchyma) of the plant and are a secondary metabolite of the photo-synthetic process.

There is no firm agreement as to their function in the plant economy. However, they are to be found in all green plants, but they are not obtained from all possible sources, in that they do not exist in sufficient quantity in the free form (terpenes) to make the recovery an economic proposition.

Even if they are not present as terpenes they will most certainly be present as a complex but locked into the molecular structure of many Glucosides. It is probably for this reason that some authorities maintain that the oils are the result of a pathological process, e.g., oleo-resins resulting from a wound to a plant,or in other cases when a plant is crushed, a ruptured enzyme bearing structure, is in contact with a normally separated glucosidal structure, and in the ensuing hydrolysis the oil is released.

The oils are to be found in greater or lesser quantities in all parts of the plant and migrate to stems and roots in an aqueous solution of plant solutes. Contrary to popular belief the volatile oils with the exception of those containing 50% or more terpenes are sparingly or slightly soluble in water. For example distilled peppermint water.

Table 10.54A Examples of solubility

This fact is also evident when water from an oil distillation process is returned to the still, an appreciable yield of oil is obtained. The solubility point is important because it provides a satisfactory answer as to the genesis, fate and excretion of the oils within the plant economy at different stages of growth, i.e., when the solute changes in volume or composition within the plant itself, precipitation occursin the vicinity of, or at the site of the plants excretory organs.

How much oil is secreted or precipitated in any one place is determined by the plant’s stage of growth, for example, oils may be directed from leaves to flowers via stems or locked into molecules of complex carbohydrates which are stored in tuberous parts; e.g., when distilling certain varieties of potatoes for spirit, a distinct odor of rose petals is noticeable. So obviously, the plant is able to direct the migration by means of solubility gradients. Because of the variable nature of plants of the same species it is common to use a descriptive term to designate solubility, i.e.,

Table 10.54B Solubility Terms

Odour Extraction 10.55
Many methods have been devised for the extraction of the essential oils for perfumes, not all of which are suitable for natural cosmetic purposes. The methods may be summarized as follows;

Table 10.55A

Maceration and Enfleurage 10.56
Both methods rely upon ‘absorption’ the major difference is temperature and technique. The Maceration method employs heated oils or fats (lipids) The Enfleurage method employs fats at room temperature. For mainly economic reasons, only a very few volatile oils are extracted by maceration or Enfleurage. Such products although of excellent quality are astronomically priced, which in turn has depressed demand in the market place.

The Maceration Method 10.57
Flower petals in linen bags are suspended in heated oil or fat. The temperature of which should not be allowed to exceed 40°C. for the best results.

The maceration time will depend upon the condition and type of material that is operated on. This is normally a minimum of 8 hours and a maximum of 48 hours.

When it is judged that the petals have yielded the perfume, the bags are removed and passed through a small roller press to express the impregnated oil. The bags are then recharged with fresh petals and the process is repeated as often as is necessary to produced the required strength of product.

If the product is an item of commerce, its strength is designated by the number of times fresh petals were extracted in the batch. Standard commercial extractive numbers are usually from 15 to 25, it will be understood that considerable time and labour are involved.

If an oil is used as the maceration vehicle, the product is known as a ‘Perfumed Oil’ or ‘Huiles Antiques’. If a fat is used. it is allowed to solidify and designated as a ‘Pomade’. Such products are then on sold for further processing. They are appropriately labeled with their extraction numbers, for example;

Violet Oil. Number 20. 1000 ml. Violet Pomade. Number 20. 800g.

TheEnfleurage Method 10.58
This method is usually reserved for very delicate odours where extraction by heated oils or fats is judged too harsh. Accordingly the room temperature method is used.

Glass plates such as standard window glass are coated in a purified fat. The fat is usually Lard (Hog Fat) Petals were then sprinkled onto the fat and left to yield the perfume to the fat. When the petals present a wilted appearance the extraction is complete. This can take between 24 and 72 hoursdepending on the composition of the petals. The flower petals are then removed and replaced with fresh for as often as necessary to reach the desired commercial strength.

Preparation of Enfleurage Plates 10.59
The easiest method is to pre-melt the fat and dip the glass plates. Take two plates together (back to back) and dip them at the same time. Support them on a wire cake rack, under which grease proof paper is placed, and allowed to cool.

A minimum of 2 mm layer will be required. If necessary the plates are dipped again until a suitable layer has been formed. The back to back plates may then be separated and are ready for use. A small airtight cupboard will be needed into which the plates may be inserted as shelves.

The purity of the oil or fat must be of the very best, lest the perfume oils are contaminated with residual odours from rancidity break down products.

Extraction of Oils by Pressure 10.60
This method is used for the citrus oils where considerable quantities are found in small oil glands within the rind of the fruit. The citrus oils have many commercial applications. For example ‘Oil of Bergamot’ this is the oil of the Bergamot orange and not that of the herbs represented by the Monarda family.

Extraction by Volatile Liquids 10.61
The volatile liquids used in commerce are usually fairly selective as to what is actually extracted and are of a low boiling point (bp) for example;

Table 10.61A

The fresh plant material is subjected to the action of the solvent. The solvent is then distilled off. This leaves a product at the bottom of the distillation vessel which is known as a ‘Floral Concrete’. The concretes are composed of oils, waxes, colouring matter and albumin etc.

The Concrete must be further processed to remove unwanted components. The product is called an ‘Absolute’. Perfumes produced by such methods are inferior to those produced by Maceration or Enfleurage. Alcohol may be used but it is considered to be non selective.

Earth Air Fire and Water
The Pharmageddon Herbal

Chapter 9
Introduction to the Pharmacy of Herbs

 

Manufacturing the Solvents and Carriers 9.1
Apart from the crude drugs and exudates, the base materials of compounding (see Mod 10), are its solvents and carriers.

The solvents are alcohol (ethanol) and double distilled water. The carriers are solutions, emulsions, mucilage’s, syrups, water and alcohol. An essential part of some carrier substances are the fixed oils and waxes. By far, the most important substance is alcohol, without it, a complete extraction of herb constituents is not possible.

Alcohol 9.2
The alcohol of the British Pharmacopoeia is a 95% mixture of ethanol and water, which is obtained by the distillation of fermented sugars or by synthesis.

It is a clear, colorless, volatile liquid. It has a burning taste, with a characteristic odor and boils around 78°C. It is miscible with water in all proportions, however, when mixing with water, a contraction of volume and a rise in temperature occurs.

The mixture must cool to 20°C before it is adjusted to its final volume. Its SG at 20°/20°C (atmosphere 20°C – liquid 20°C), is 0.8119, for practical purposes we can say 0.800, its molecular formula is C₂H₅OH, sometimes given as C₂H₆O.

Synthetic alcohol can be manufactured by various chemical routes, from different starting substances, e.g.;

Ethylene C₂H₄ or Ethyl amine C₂H₅NH₂ or Ethyl Iodide C₂H₅ I.

The most common starting substance is Ethylene; The alcohol produced by such methods is cheaper, and therefore, attractive. On analysis, its formula is C2H5OH, however, there are quite subtle differences that are unexplainable from a non Vitalist chemical viewpoint.

For want of better terminology, I will call such substances ‘dead alcohol’. The physiological effects are manifestly different to those of alcohol produced by fermentation methods. From the vitalist point of view, those differences are quite obvious.

What is produced is determined by the strain of the yeast and the material (substrata) upon which the yeast must work. The great perfume houses of the world know this to be a fact; and in spite of their high tech shiny laboratories, it still takes the human nose to detect what the chemist cannot. The perfumers preference, is for a grain based alcohol to produce the ethereal and elusive top notes of fine perfumes.

Whereas, for the Herbologist, a fruit or herb based alcohol is the preferred solvent. Such preferences are not a matter of philosophy or mere quirks of trade, but are the result of many generations of experience, that cannot be reduced to dry and tidy chemical formulae. What science cannot measure, it will turn a blind eye to.

Alcohol is produced within the body by the same, or similar, type of enzymes used by yeast, and the body recognizes the molecules produced by nature. In some countries it is illegal to use industrially produced alcohol for beverages or medicines. For ethical and safety reasons, the only alcohol to be used is that produced by the fermentation method.

Fermentation 9.3

‘The fungi in common with other living organisms possess tools or reagents far more specific, more delicate and more powerful than those available in the laboratory’.
Lilly and Barnett
Physiology of the fungi 1951.

The tools or reagents referred to are, of course, ‘Enzymes’. The alchemists of life, which at bio-temperatures perform electron and proton chemistry at dazzling speed., e.g., one molecule of an enzyme called ‘urease’, can hydrolyze 30,000 molecules of ‘urea’ in one second. Without urease, it would take around 3 million years.

All life functions are enzyme functions. There are many thousands of different enzymes that work upon different sub-strata for different results. We cannot make enzymes, we must borrow them from nature. Many of the enzymes will only work in the presence of co-enzymes, which are other substances, such as vitamins and minerals. Each type of enzyme produces co-enzymes that are required by other tribes.

The study of fungi, is embraced by biology and microbiology, and is called ‘Mycology’ and more specifically, for our purposes, ‘Industrial Mycology’. The art of fermentation has a recorded history of around 8,000 years, its study as a science, covers around 250 years, and it is still in its infancy.

Yeasts are a single cell fungi. As micro-organisms, they are of great variety and differ in shape and function. They are of great importance in the pharmaceutical production of organic acids, antibiotics, vitamins and other enzyme preparations. The technology is relatively simple, because living organisms do the work, we need only provide materials and the right conditions.

Figure 9.3A

The following figure is taken from ‘Lowsons Botany 8^th Edition 1939

 

Yeast Strains 9.4

There are many different types of micro-fungi which are cultivated to perform specific tasks. Our interest is in the production of alcohol for extraction of crude drugs.

We may do that by the use of ‘Bakers’, ‘Brewers’, or wine yeasts, which belong to a sub-family called ‘Saccharomycoideae’, or the ‘sugar fungi’.

The above mentioned yeasts belong to the tribe S.cerevisiae, and the variety S.ellipsoideus. The resulting alcoholic soup will be distilled to produce the ethanol required for extraction purposes, so we have no interest in bouquet or flavor.

Yeast Ecology 9.5

As in all living things, yeast must eat, breathe, excrete and reproduce itself. The success or otherwise, of those functions is determined by its environment. For the purposes of this module, if the word ‘yeast’ is used, it should be taken to mean members of the sugar fungi.

Yeast Food 9.6

Yeasts utilize their nutrients in solution. The substrata, or food is dissolved by the extra cellular excretion of enzymes. The term ‘enzyme’, means ‘in yeast’. The enzymes are proteins and will often need co-enzymes to kick start them.

Some common co-enzymes are; Carbon, Nitrogen, Phosphorus, Potassium, Magnesium, Iron, Zinc, Copper, Manganese, Molybdenum and Calcium. Each of these elements should be freely available from plant substrata, however, if yeast were put to work on white sugar alone, it would also need to be fed vitamins and minerals to substitute for the missing co-enzymes. For example, lack of nitrogen during fermentation will cause the living yeast to break down the dead yeast cells to sequester the needed nitrogen. This process is called dehydrate-amination, which is the primary reason for the production of excess ‘Fusel Oils’. The term is from the German ‘evil spirit’, commonly called, ‘rot gut’. The Fusel oils are a mixture of the amyl alcohols, i.e., amyl, isoamyl, isobutyl, hexyl and propyl; all of which are extremely toxic and responsible for the headaches, nausea and gastric upsets caused by poor quality wines and spirits. So the better the substrata, the better the alcoholic soup. This means less waste and less work at a subsequent stage.

Yeast Respiration 9.7

Fermentation may take place either in the presence of the atmosphere with free oxygen (aerobic), or when completely excluded from the atmosphere, which is called ‘anaerobic fermentation’. However, water and oxygen are essential to life, so that if the fermentation takes place anaerobically, then the oxygen will be taken from the water or breakdown products. It is usual to conduct the fermentation in anaerobic conditions, because of the danger of contamination, from unwanted yeasts, e.g., vinegar from the bacteria ‘Acetobacter’. The substrata, which is known as the ‘Must’, is usually sterilized by metabisulphite to kill any unwanted intruders, prior to the fermentation process.

Environmental Acidity 9.8

The acidity of a ‘must’ (fermentation liquid), will stimulate or inhibit the fermentation process. Experimental results suggest that sugar fungi give optimum performance in a liquid with a pH of 4 to 4.5. If fruit is the basis of the substrata, then there is usually sufficient organic acid, such as citric, malic or tartaric to acidify the liquid.

It is always prudent to test. If acidification is needed, then the readily available citric acid is most convenient. The purified compound may be used, but it is inferior to lemon juice. A small lemon approximates 3.5 g of citric acid. Under no circumstances should strong acids, such as hydrochloric, nitric or sulphuric, be used.

Fermentation Temperature 9.9

Enzymes facilitate biological reactions. All chemical reactions involve a release or transfer of energy, which may be detected as temperature fluctuations. If heat is absorbed from the environment in which the reaction is taking place, it is called an ‘endothermic’ process and the temperature will drop. If heat is evolved from a reaction, it is an ‘exothermic’ process and the temperature will rise.

The conversion of sugars to alcohol by enzymes is an exothermic process, and heat is evolved. This must be remembered if using heat for the temperature control of the fermentation liquid. Problems may be circumvented by using a thermostat.

The correct temperature will ensure a brisk and efficient fermentation. The best temperature is around 25°C. Temperatures of 30°C and over will result in the steady demise of a yeast colony. Low temperatures will cause the fermentation to become sluggish. Below 7°C fermentation will cease, which is a major reason for a stuck ferment. If this proves to be the case, then a rise in temperature will start the yeast working again.

The Fermentation Substrata 9.10

The sugar fungi, as the name implies, use sugars for food and excrete ethanol (alcohol). The process is multi-stage and carried out by enzymes; like the production of starch, this is a process which is beyond our knowledge and we utilize the yeast, or the isolated enzymes to perform the molecular engineering involved.

The sugars belong to a class of substances called the carbohydrates, which are sometimes designated CHO. However, not all compounds that fit that description are carbohydrates, for example, Acetic acid C₂(H₂O)₂.

For our purpose, the most important carbohydrates are the sugar and starches. Sugars, which contain six or less carbon atoms in the molecule, are called ‘Monosaccharides’. Sugars that contain 12 Carbons per molecule are called ‘Disaccharides’.

The starches which have a large number of carbons per molecule are called ’Polysaccharides’. The names of the different sugars always end in ‘Ose’ e.g. Glucose, Fructose, which, because they have 6 carbon atoms per molecule, are known as ‘Hexose’s’, from the Greek ‘Hex’ meaning six. Sucrose may be considered to be formed by the elimination of water (condensation reaction), from two hexose molecules, so it is a ‘disaccharide’. Di, is also from the Greek meaning twice.

The starches are formed from many (Poly) hexose units. An approximate molecular formula is (C₆H₁₀O5)₃₃₀, i.e. about 330 hexose units. The starches are found in all green plants, while the sugars are found in abundance throughout the plant kingdom; fruits, roots and leaves may be used in solution by enzymes. Alternatively, a hot water extract of the plant material can be used as the substrata for ethanol production.

Sugar and Starch 9.11

Table 9.11A

Substance	Glucose	Fructose	Sucrose	Starch
Formula	C6H12O6	C6H12 O6	C12 H22 O11	(C6H10O5)n
Occurrence	Grapes	Most Fruits	Sugar Cane	Nearly all plants
Occurrence	Honey	Most Fruits	Sugar beet	Nearly all plants
Type	Monosaccharide	Monosaccharide	Disaccharide	Polysaccharide

 

Glucose is sometimes called Dextrose, or Grape sugar. It occurs naturally in grapes, honey, most sweet fruits, and may also be found in smaller quantities in many plants.

Glucose is manufactured on an industrial scale by hydrolyzing starch with dilute hydrochloric acid under pressure. The HCI is then neutralized, and the syrupy mixture evaporated under low pressure.

The syrup is sometimes called corn syrup, irrespective of the starch source. The syrup is not pure glucose and it may also contain dextrin and maltose. It is in great demand by the food and beverage industries. Corn syrup is suspect and especially in the USA where the bulk of it is made from GM organisms and that includes the yeast.

It must be mentioned that glucose is reduced with a sodium/mercury Na/Hg amalgam, to produce Sorbitol, which like glycerol, is used as a humectant (moisturizer). Glucose is soluble in water, but sparingly soluble in alcohol.

Glucose and Fructose are ‘isomers’. Glucose is optically active and rotates polarized light to the right, hence it is sometimes called ‘Dextrose’. Sucrose is the most common of all sugars, and is to be found throughout the plant kingdom.

The commercial source is from sugar beet, which can give up to 20% by weight of sucrose, or from sugar cane, which yields far higher; it is soluble in water but almost insoluble in alcohol. Its melting point is 180°C, at temperatures above that it starts to decompose. It can be hydrolyzed by boiling in water for around 20 minutes. Sucrose is dextra-rotary, and with boiling water it splits into an equimolar mixture of glucose and fructose, which is called ‘invert sugar’.

Inversion of Sucrose. Figure 9.11A

Inversion by the Boiling method

 

Sucrose C₁₂ H₂₂ O₁₁ + Water H₂O = C₁₂ H₂₄ O_12. Boil for 20 minutes à Glucose + Fructose

 

The yeast enzyme ‘sucrose’, or as it is sometimes called, ‘invertase’, carries out the process at low temperatures, from 30°C down to 10°C, and depending on the balance between the sugar and invertase, the reaction takes just seconds.

Starch is so common and in such abundance, that we tend to forget how important it is; without it animal life could not exist, so we are dependent on the synthesis of the green plants to produce it. We do not know how plants do that.

The plants use it as a reserve food supply. The bulk of the worlds commercial supplies are obtained from a relatively small number of plants, e.g., wheat, potatoes, maize, barley or rice. There are, of course, many other sources which are utilized. It is obtained by grinding, washing, filtering and drying the base material.

The microscopic examination of starch granules show a variation in shape from plant to plant. A typical green plant contains around 7% by weight, whereas, roots or tubers can contain upwards of 90%. Starch is a polysaccharide, it has large numbers of hexose units linked together, which must be broken down to obtain the sugars. The hydrolysis occurs in stages, and is not complete because the glucose syrup also contains dextrin and maltose, the probable pathway is as follows.

Figure 9.11B.

Starch – Dextrin – Maltose – Glucose.

This, of course, is the basis of the malting process of grains; for the brewing of beer; essentially the grains are sprouted, in this way enzyme activity is promoted to carry out the hydrolysis. The sprouted grains are then killed and brewed.

Yeast, Enzymes and Alcohol 9.12

Sugars occur in all life forms in great numbers and great variety; they will also have an enzyme that facilitates their conversion to other substances needed for the life process. When an enzyme has completed its task, it passes the molecule to an enzyme of another type for a further modification. Only a very few of these production lines, or cycles, have been identified.

It is one thing to describe the microscopic form of a living object, and then to describe its product, as though the object were isolated and frozen in time. The reality is, that everything is happening at great speed, and when a neuron fires, every other neuron must know, because that is the only way in which life can maintain that synchronicity essential to viability. When an enzyme performs its task every other enzyme must also know.

The conversion of sugars by yeast to alcohol, is performed by enzymes; over a dozen have been identified; the total of which is called the ‘Zymaze Complex’, all of which are involved in the fermentation process. Not all of the functions are understood. The most important enzymes, from the alcohol production point of view, may be summarized as follows.

Table 9.12A

Enzyme.	Alternative Name.	Substrata.	Product.
Amylase.	Diastase.	Starch.	Maltose + Dextrin.
Maltase.	……………………	Maltose.	Glucose.
Sucrase.	Invertase.	Sucrose.	Glucose + Fructose.
Zymaze.	……………………	Glucose/Fructose.	Alcohol + CO2.

It must be clearly understood, that the clear cut divisions between substances and sugars that are shown in Table 9.11A, only indicate the major type of sugar to be found in a plant, for they will undoubtedly contain a complex of sugars, in the same way the yeast will secrete a complex of enzymes to handle the substrata. The processing and sequential ordering in such short time spans defies the imagination.

In human terms, we are talking of a combined oil refinery, sugar refinery and a distillery, which would employ large numbers of chemical engineers, chemists, technicians and tradesmen, plus the ancillary labor. Even after such enormous expenditures of money, time and energy it is no more than a pale shadow of the natural process. The sequential ordering of the process, depends upon the substrata on which the Zymaze complex goes to work. What we think happens, is as follows;

Figure 9.12A. The Starches.

Starch – Water – Amylase – Maltose – Water – Maltase – Glucose – Zymaze = Alcohol + CO₂

Depending on the type of starch and other sugars present, this process could be considerably modified, and other pathways selected.

Figure 9.12B. Sucrose.

Sugar – Water – Sucrose – Glucose + Fructose – Zymaze = Alcohol + CO₂

 

Figure 9.12C. Glucose and Fructose.

Glucose and Fructose are isomers, therefore the formula weights are identical.

Isomer + Zymaze = Alcohol + Carbon dioxide

2C6 H12 O6 + Zymaze = 2C2 H5 OH + 2CO2
(180g)                                      (92g)         (88g)

1 mole of sugar is its formula weight, which corresponds to 180 gm. Figure 9 -12C, shows that 1 mol sugar yields 2 mol alcohol and 2 mol Carbon dioxide.

The formula weight of ethanol produced is 92 g, and that of carbon dioxide 88 g. On the basis of molecular weight, then 51.1% of the sugar is converted to alcohol and 48.9% to carbon dioxide. Obviously, that is the theoretical yield, because the yeast and the enzymes must use some of the sugar for their own metabolism.

The actual yield, under good conditions will vary between 40 to 48% ethanol per unit of sugar, i.e. 400 to 480g of alcohol per kg sugar; that will correspond to 352 to 423 ml of alcohol per kg of sugar, based on the density of the alcohol as 0.811 g/ml. It must be remembered, that the original sugar was in solution before conversion by the Zymaze complex, into alcohol.

The % of alcohol by volume, is dependent not only on the weight of the starting sugar, but also on the volume of the solution. The amount of alcohol produced per unit of sugar, is dependent on the yeast and its environment, therefore, a constant is not possible. Accordingly, further Figures and Tables will be based on the assumption of a 45% by weight conversion, of sugar to alcohol.

Sugar and Alcohol in Solution 9.13

If 1 kg of sugar will convert to 45% by weight of alcohol, then 1g of sugar will produce 0.045% of alcohol by weight, so we may now set up a simple equation.

Weight of sugar in grams x 0.045 ÷ by the volume of the solution = % of potential alcohol.

1000g x 0.045 ÷ 5 litre = potential alcohol 9% by volume in 5 litres = 450ml per 5 litre

 

It will be understood from Table 9.11A, that most plant materials will yield some sugar or starch. If the starting material were grapes or other fruits, then they could be crushed and pulped and the juices fermented directly, or if the starting material was leaf, root or tuber, then they must be first chopped or ground, and the starches and sugars extracted by hot water treatment.

The method used to determine the sugar in solution, and therefore its potential alcohol, is by measuring the density of the solution. We could do this by weighing a volume, however, it is much more convenient to use a Hydrometer, which is simply ‘floated’, in the solution. The reading is compared with a set of Tables from which the appropriate values are taken.

The Hydrometer 9.14

In Module 4.32, we discussed the subject of ‘Relative Density’, or specific gravity (SG). Water is the substance, against which other substances are measured, in terms of their density.

Water is given the arbitrary number of ‘one’, and it is usually written as 1.000. If a miscible solute is lighter than water, its value will be below 1, e.g. 0.955, if it is heavier than water its value will be above 1, e.g., 1.110. Alcohol has an SG of 0.811 (lighter than water), therefore, if we add alcohol to water, we lower the density of the water.

Alcohol is miscible with water in all proportions, therefore, the density registered on a hydrometer, will be above 0.811 and below1.000 , e.g., if such a solution is 10% alcohol by volume, its SG is 0.986. If a solute is heavier than water, e.g., salt or sugar, then the density shown on the hydrometer will be above 1.000., e.g., if a volume of water contained 10% sugar by weight, its SG would be 1.075. Tables for sugar and alcohol will be given.

At the commencement of 4C there is an image of the old Sikes Hydrometer which was used by the revenue collecting agencies for determining the strength of alcohol in a solution. Today the hydrometer has been considerably improved and many different types of scales are available for differing purposes such as the measurement of sugar in solution. Also available are electronic instruments however they are dependent on a power source.

 

Figure 9.14A

On the left is shown a universal scale which would be suitable for alcohol and sugar solutions. Next to it is a hydrometer which contains the scale. The hydrometer shown is a sophisticated model that contains its own thermometer.

If the density of the water is lowered, by the addition of alcohol, the graduated hydrometer will sink lower; if the gravity is raised, by the addition of sugar, the hydrometer will rise. The hydrometer is simply a sealed glass, or plastic tube, which is weighted at one end. The tube is calibrated against distilled water at a given temperature, and then scaled in degrees according to the liquid it is designed to measure. For example, and for the purpose of taxation, the British authorities use the Sikes Hydrometer, of which the strength of an alcoholic solution is denoted as degrees over proof (o/p), or degrees under proof (u/p). The standard, or Proof Spirit, is legally defined as 57.07% v/v alcohol. (This is approximately 0.918 SG). The instrument used scientifically, is scaled to relative density or SG. There are three other scales in common use;

1. Degrees Baumè (Be°), named after Antoine Baumè, a French pharmacist. The scale is graduated to read the potential alcohol content of a must, or solution, prior to fermentation. Each degree indicates a possible 1% alcohol by volume, so it is related to the amount of sugar in the solution. Degrees Baumè will be used in conjunction with SG in the ‘Sugar Solution Table’.

2. Degrees Brix, sometimes called Balling. The scale is graduated to read the % of sugar by volume in a liquid. Each degree indicates 1% sugar by volume.

3. Degrees Twaddell (Tw°). The scale is graduated from 0 to 200°. An SG of 1.000 represents 0 Tw°. Each degree Twaddell represents 0.005 SG.

For practical purposes, the Twaddell scale is of more use to us than the Brix/Balling scale, for calculating the weight of sugar in a must or sugar solution. The Baumè scale may be used..to calculate the potential % of alcohol by volume of a sugar solution or must. Before we proceed to look at the relationship between the scales, let us assemble some conversion factors, whereby, the scales can be proved.

Conversion Factors, Table 9.14A.

S.G. Alcohol (95%).	0.811	Liquid.
S.G. Starch (average).	1.148	Varies between 1.142 to 1.152.
S.G. Cane Sugar.	1.158	Crystallised solid.
S.G. Distilled water (4°C).	1.000	Tap or Spring contains solutes.

Sugar % by volume (ml) to % by weight (g) x 1.580
Sugar % by weight x 0.045 = Potential alcohol by volume.

1 g sugar will increase the volume of a liquid by 1.63 ml.

Or 1 kg increases 1 litre by 630 ml at 20°C.

Relationship of Density Scales, Tables 9.14B.

In the following Table, Tw° represents % sugar by volume, and Be° represents % of potential alcohol by volume. The sugar volume to weight ratio are based on 5 litre batches. For larger volumes, multiply by the factor shown.

 

SG°	Tw° Sugar	Be° Alcohol	Sugar Volume.	Sugar Weight	Gravity	10 L	15 L	25 L
1.005	1	0.7	50	79.5	5	X 2	X 3	X 5
1.010	2	1.4	100	159.0	10
1.015	3	2.1	150	238.5	15
1.020	4	2.7	220	318.0	20
1.025	5	3.4	250	397.5	25
1.030	6	4.1	300	477.0	30
1.035	7	4.7	350	556.5	35
1.040	8	5.4	400	636.0	40
1.045	9	6.0	450	715.5	45
1.050	10	6.7	500	794.0	50
1.055	11	7.4	550	873.5	55
1.060	12	8.0	600	954.0	60
1.065	13	8.7	650	1033.5	65
1.070	14	9.4	700	1113.0	70
1.075	15	10.0	750	1192.5	75
1.080	16	10.6	800	1272.0	80
1.085	17	11.2	850	1351.5	85
1.090	18	11.9	900	1431.0	90
1.095	19	12.4	950	1510.5	95
1.100	20	13.0	1000	1590.0	100
1.105	21	13.6	1050	1669.5	105
1.110	22	14.2	1100	1749.0	110
1.115	23	14.9	1150	1828.9	115
1.120	24	15.4	1200	1908.0	120
1.125	25	16.0	1250	1987.5	125

 

SG and Weight/Volume Relationships, Table 9.14C.

SG 20°/20°	Weight g/ml	Volume/ml	Remarks.
0.790	0.790	1.265	Theoretical 100% Alcohol (Dehydrated)
0.800	0.800	1.250
0.811	0.810	1.245	95% Alcohol by Volume
0.830	0.830	1.204	90% Alcohol by Volume
0.860	0.860	1.162	80% Alcohol by Volume
0.887	0.880	1.149	70% Alcohol by Volume
0.910	0.910	1.098	60% Alcohol by Volume

Using the Tables 9.15

Distilled water is at its most dense at 4°C, at a higher temperature, a given volume of distilled water will increase in volume and decrease in density.

For this reason, most hydrometers are calibrated at 20°C. The reading is taken where the scale cuts the liquid. The calibration temperature will be given on the hydrometer.

Assume that we have prepared a ‘must’ for fermentation, and bearing in mind that the sole purpose, is to produce a fermented liquid with the highest possible alcohol content, and the lowest possible level of unfermented sugar, we need to set a target level, for example 14.9% alcohol by volume.

Refer back to Table 9.14B, and seek out 14.9, in column 3, which is the Baumè Scale. The SG in column 1, reads 1.115. The sugar content in grams, column 5, is 1828.9; round that figure to 1830 grams per 5 litres. We proceed as follows.

A. Example; Take the SG of the must or liquid. Assume the SG is 1.032.

B. From that figure we deduct 0.007, to allow for un-fermentable solids, such as gums and pectin;

SG of must = 1.032  Deduct = 0.007  Correct SG = 1.025  An SG of 1.025 = 397.5 g sugar in 5 litres.

C. Target level 14.9 Alcohol SG 1.115, sugar 1830 g.

Target SG = 1.115 = Gravity 115 (column 6)

Actual SG = 1.025 = Gravity 25 (Column 6)

Gravity Difference = 90 (Column 6)

Seek out gravity 90, in column 6, then look to column 5, and you will find sugar 1431 g. That is the amount of sugar, to be added to the must, to reach the target level of 14.9% of alcohol by volume in 5 litres.

If we wish to produce 10, 15, or 25 litre batches, then the sugar weight in column 5, must be multiplied by the factor shown. The values given in columns 1, 2, 3 and 6 do not change.

 

Chapter Continues as 9B

 

Library
Pharmageddon Herbal Block Index

 

 

 

Earth Air Fire and Water
The Pharmageddon Herbal
Essential Concepts of Chemistry
Chapter 7 Part 2

Introduction.
Optical Activity is an inherent power, of biological substances. The Polarimeter is simple enough to construct once the principles have been grasped. It may be made from wood and metal fittings, or other convenient fabricating material.

The image on the left is a very early model manufactured by a company called Gallenkamp and gives a fair idea of the principles. The analysers of today are considerably more sophisticated and cost a great deal of money. 

A natural substance will produce a characteristic rotation signature which is used for identification purposes when examining a sample.

The concept, of a shape of a molecule in space, helps us to understand why synthetic molecules, wreak so much damage and disruption, when taken into a structure composed of natural molecules.

 Stereo Chemistry 7.23
In section 7.14, we touched on the subject of isomers, i.e., compounds that have the same molecular formula but the atoms are arranged in a different way, which results in differing chemical and physical properties.

Stereo chemistry deals with the structure of molecules and the position of the molecular atoms in 3 dimensional space. Therefore, we have the further concept of Stereo-isomerism, in which the isomers have the same formula and functional groups, but the atoms are arranged differently in space, which also results in different properties. Stereo isomers govern most of the reactions that occur in a living system.

Structural Representation 7.24
Let us consider a simple molecule of Methane, the molecular formula is CH₄.

Molecular geometry is a means of studying the manner in which atoms arrange themselves around a polyvalent central atom, and then the further concept of bond angles. It has already been stated that Carbon is tetravalent, i.e., forms 4 bonds. It has been determined that the Hydrogen bond angles are 109.5° which means that a molecule of methane will have the geometry of a tetrahedron as follows.

Figure 7.24A

All carbon atoms that have 4 single bonds will have a tetrahedral structure, e.g. Chloroform (CHCl₃). Most bond angles are constant enough to be considered normal for a particular atom and its state of valence,

1. Water (H₂O) Bond angle 105°

2. Ammonia (H₃N) Bond angle 107°

3. Hydrogen sulphide (H₂S) Bond angle 92°

Molecules and Mirrors 7.25
Mirrors and the reflected object image that we observe are so commonplace that we rarely stop to think of what it is that we see. There are two types of mirror image.

1. Those that may be super imposed on each other, e.g.

Figure 7.25A

The rules of the game state, that for an object to be super imposable on its mirror image, it is permissible to slide one across the other, such as a circle or a square; or if the mirror image is rotated through 180° and a match is made, then the object is symmetrical.

In Figure 7.25A, molecule 2 is the reflected image of molecule 1. If molecule 2 is rotated through 180° it will have the same geometry as molecule 3. Molecule 3 is then identical to (super imposable) molecule 1. Any molecule that meets that criterion is called an Achiral molecule, irrespective of its structure.

2. Mirror images that cannot be superimposed on each other are said to be Chiral (ky-ral). The word chiral is from the Greek ‘chier’ meaning ‘hand’. For example, hold your right hand up to a mirror, palm forward, the mirror image that you see is that of the left hand. Compare the palm of your left hand with the image in the mirror. Such structures are asymmetrical or chiral.

Enantiomers 7.26
When the molecular structure of two substances are related to each other, as in the non super imposable, left and right hands they are called Enantiomers. The word is compounded from the Greek, ‘enantio’ meaning ‘opposite’ and ‘meros’ meaning ‘part’. Molecules the have this left and right hand relationship are called an Enantiomeric Pair.

Chiral molecules will react in the same manner as Achiral molecules, i.e. Enantiomers will have the same physical and chemical properties, however the rate of reaction differs which gives them different biological properties and they also differ in optical activity.

The ‘R’ and ‘S’ Convention 7.27
The ‘R’ and ‘S’ convention, is a general method, of naming the left or right handedness of stereo isomers. The ‘R’ is taken from the Latin ‘rectus’ meaning ‘right’ or ‘clockwise’. The ‘S’ is taken from the Latin ‘sinister’ meaning ‘left’ or ‘anticlockwise’.

An added advantage of this system is, that a chemist, by prefixing the name of a compound with an ‘R’ or ‘S’, can indicate the arrangement, of the four different groups, around a chiral carbon.

To make use of the system the groups around the central carbon are assigned a priority according to their respective atomic numbers. The greater the number, the higher the order of priority.

The atom or group with the lowest priority, i.e. the lowest atomic number, is placed behind the chiral center. The atom or group with the highest priority, i.e. number one is placed at the top. From this position if the next highest priority falls to the right of the chiral center, i.e. a clockwise direction, it is an ‘R’ stereo isomer and if to the left, it is the ‘S’ form,

Figure 7.27A

 

The shaded area represents the atom or group which has the lowest priority

 

In para.7.26 it was stated that the (R) and (S) forms of an Enantiomeric pair have different rates of reaction and exhibit different biological behavior, for example, it is known that the (S) form of the alkaloid nicotine has a greater toxicity than the (R) form. The (R) and (S) form of some artificial sweeteners is also detectable. A further much quoted example is that of Carvone, which a naturally occurring constituent of many umbelliferous plants is. The (R) and (S) forms have different odors.

Figure 7.27B

Many enzymes are known to be stereo specific, they will interact with one form and not the other. This fact alone should send shudders down ones spine and it offers a further explanation of the huge increase in disease and mortality of mankind. The plants that we use for food and medicine have balanced R and S structures. The synthetics which have been introduced for flavours cosmetics and medicines do not. Even when the chemist knows which is the preferred form, they are not able to resolve the mix which they have constructed. The havoc and damaged that this has caused is beyond dispute. The synthetic mirror images in many cases passes straight the the walls of the intestines where as the natural substance if harmful would be blocked. The folic acid situation is a case in point.

Optical Activity 7.28  
In 1808, a British chemist and physicist W H. Wollaston predicted molecular geometry. Possibly the insight was stimulated by his interest in light and crystals, for amongst other things, he invented the reflecting Goniometer which is a device that measures angles on crystals. At our current state of knowledge we may see clearly how he arrived at the concept of molecules in three dimensions .. I wonder what the molecules look like in all of the  7 dimensions?

Not surprisingly, the evidence for molecular geometry started to accumulate in the area of crystallography. Suffice to say, that in 1815 the French physicist J.B. Biot demonstrated that natural organic compounds, whether liquid, or in solution, rotated the plane of polarized light to a greater or lesser degree depending on the substance. Such substances were said to be Optically Active.

Polarised Light 7.29
If light is passed through a suitable filter, light of a uniform wavelength is produced. The light will vibrate in all planes from 0 to 360°. If the light is then polarized it will only vibrate in one plane. A common example of a polarizing filter is that of the well known Polaroid sunglasses. A simple example of the polarizing of light follows.

Figure 7.29A

When an optically active substance is placed in the path of a beam of polarized light, the beam will be deflected, or to use the correct term, it will be rotated. The angle of the deflection is noted and it is called the ‘Observed Rotation’.

The Polarimeter 7.30
The observed rotation of a compound is a physical property which is used for identification purposes. Chiral molecules which have different shapes will deflect light in a different plane.

The Polarimeter is the device that is used to study and identify optically active substances.

Fig 7.30A

 

The apparatus is enclosed in a tube which has a port incorporated for the insertion or removal of the substance to be investigated. The Polarimeter must first be calibrated, the procedure is simple. With the Polarimeter empty, the light is turned on and an observation made.

If light is observed the analyzer lens is rotated until the light is blocked and the field of view is dark. The reading is taken from a scale usually attached to the Analyser lens. A number of readings may needed. Especially if the instrument is of an older type. This position of dark field is as represented in figure 7.29A

A liquid sample of the substance to be investigated, commonly called the cell, is inserted into the body of the Polarimeter. If the sample is optically active it will alter the polarization of the light and it will pass through the analyzer lens, as represented in diagram ‘A’ Figure 7.29A.

To ensure accuracy, several readings of the observed rotation must be made. The analyzer lens is rotated until the field of view shows maximum light intensity. From that position the analyzer is rotated until the light is blocked and the field of view is once again dark. If the analyzer must be rotated to the left to restore the dark field, the optically active substance is said to be Levorotatory , and if to the right, Dextrorotatory.

Figure 7.30B

If the substance under examination does not pass light through the analyzer lens, and the field of view remains dark, the substance is said to be Optically Inactive.

The Racemate 7.31
The (R) and (S) forms of chiral molecules are optically active. However a 50/50 mix of (R) and (S) (+ and -) enantiomers is optically inactive because the optical rotation of one enantiomer is balanced by the opposite optical rotation of the other. Such mixtures are called ‘Racemates’.

The term is from the Latin ‘racémus’, meaning ‘bunch of grapes’. Racemic acid is an isomeric modification of Tartaric acid which is often found in grape juice. The term Racemisation means the conversion of an optically active substance into an optically inactive substance. Any enzyme which will catalyze the conversion of an optically active into an optically inactive compound is known as a ‘Racemase’.

Chirality and Biological Systems 7.32
Without doubt chirality is a major factor in all of those reactions that mediate the essentials of life, in whatever form it may be found. Generally, nature will only produce from the possible stereo isomers the one that is the most active, e.g. menthol from oil of peppermint. A further striking example is that of D-glucose, which has 16 possible stereo isomers. D-glucose is a product of photosynthesis in green plants and is the only one produced from the possible 16.

D-glucose is used to power bodily functions in humans, without it we could not exist. Science does not know how to create optically active substances, although they can propagate chirality by borrowing from nature. However, as stated previously such procedures have led us to the brink of disaster.

Chirality and Synthetic Drugs 7.33
Between them, the Trans-National Pharmaceutical Companies market many thousands of synthetic compounds on a global basis. Of that figure around half may be classed as semi-synthetic, i.e. they have a borrowed chiral structure. Approximately 80% of the semi-synthetic compounds are racemates. The remaining synthetic compounds are achiral and are not able to undergo ‘Resolution’, i.e., the separation of ‘R’ and ‘S’ enantiomers. In many cases it is impossible to ‘Resolve’ a racemic mixture. Where the resolution is possible, the compound may have to be routed through 10 or 20 biosynthetic stages to achieve the resolution, such procedures can be length and also extremely expensive. Consequently the majority of the pharmaceutical preparations are Racemates. Until adequate safeguards are introduced the chemical and pharmaceutical industry will continue to market a product on purely economic criteria which is killing us all.

Lethal Racemates 7.34
When and if the medical historians are finally able to write a definitive history of the 20^th century orthodox medicine, they will have a burgeoning catalogue of medical disasters upon which to draw. Medicine is ‘Big’ business, and like big business everywhere, they are supported by cohorts of unscrupulous lawyers, crooked politicians and renegade scientists, they are often involved in chicanery, cupidity and stupidity. All of which has been visited on an unwitting public. The drug companies have labeled their joint products as ‘Ethicals’, one cannot help but see the droll cynicism behind such a name. Especially when the reported fatalities from orthodox medicine exceed the million mark on an annual basis. 

The sort of problems found with the racemates are not confined to the prescription only drugs. The over the counter (OTC’s) drugs and pharmacy only medications (POM’s) are generally considered to be safe and yet, the ubiquitous Aspirin is estimated to be responsible for around 5% of fatal poisonings each year. The much used anti-inflammatory, antacids and laxatives are estimated to account for 20% of all drug related hospital admissions.

The major point to be made is, that many of the drugs implicated in fatalities and extreme reactions had been on the market for a number of years before being withdrawn. Given the evidence surrounding the synthetic and semi-synthetic drugs, the problem must only represent a small percentage of the total.

The Herb as Manufacturing Herbalist 7.35
In discussing chemical structures, we have necessarily had to deal with the subject, as isolated compounds frozen in time. This is an illusion, when we look at a living organism, we must understand that everything is happening at once and at speeds of up to 30 thousand times per second. If we considered the earth as an organ system within a solar organism, then we may understand that the earth and everything that is on, or in it, is part of an incredible chemical equilibrium reaction. The synergy of which is plainly visible on the macroscopic scale, i.e., everything is connected to everything else. The closeness of the relationship is only a matter of a degree. The biosynthesis of carbon compounds by a plant is not fully understood, however by use of radio active markers, and a lot of hard work, the biosynthetic pathways used by plants have been lightly sketched in;

Figure 7.35A

For the purpose of clarity figure 7.35A is a very simply representation. Each division is responsible for many compounds of great complexity. For example, Chlorophyll is the major pigment involved in the photosynthetic process. Its structural representation is as follows;

Figure 7.35B

 

It will be seen that the head of the chlorophyll is a complex ring structure which contains many carbon, carbon double bonds, which are very reactive.

The head is the receptor site for in coming solar energy.

The long carbon tail is embedded, or anchored in a special type of cell called a chloroplast.

Photosynthesis is sometimes described as a reverse respiration process, carbon dioxide is taken in and oxygen is given out. In that respect it is interesting to note the similarity of structure between haemoglobin, which carries oxygen to the tissues of humans, and that of plant chlorophyll. Haemoglobin contains iron (Fe) at the center of its ring structure instead of Mg and contains two extra nitrogen atoms.

From the point when the first leaf shoot of an embryo plant, commence to photosynthesize, a great cascade of biochemical reactions are set in motion supreme alchemy and transmutation at bio temperatures.

At low bio temperatures, and at great speed, many thousands of intricate compounds are constructed. Some are for immediate use and some for storage, while many others are precursors of further synthesis.

Amino acids, enzymes, hormones, nucleic acids, steroids, vitamins, all in great profusion, and unlike the pharmaceutical synthetics that can only provoke a single pharmaceutical response, medications based on the whole plant not only act synergistically, but the action is bolstered with nutritional supplements.

The plant compounds are the same as, or very similar to those found in the human body. In 1970, Lynn Margulis at Boston University, caused an uproar when she advanced the view that the cells of the higher organisms, the eukaryotes, began as communities of prokaryotes, which are single celled organisms. That strongly suggests common ancestry for all life forms, i.e., evolution by division and symbiosis. However, just like the anthropoid theory, it is anybodies guess because we are talking about a timescale of at least 600 million years.

 

One perceives the fundamental essence of life in the living, not the inanimate, in that which is changing, not in what is finished.

Goethe.

-::-::-

 

Acids, Bases and Salts 7.36
Acid and base reactions are an important function in all living systems. Such reactions may occur spontaneously, simply as a result of mixing reactants. When acids, bases or salts are dissolved in water they dissociate, the molecules break up and the particles become ionized. Such particles are called ‘electrolytes’, because the solution that contains them will conduct electricity.

Acids 7.37
Acids have a number of chemical properties in common;

1. In the pure form they are non-electrolytes, they do not conduct electricity, if dissolved in water they will.

2. They contain hydrogen atoms.

3. They react with alkali or bases to form salts and water.

4. They will react with carbonates to form salts, carbon dioxide and water.

When a non metallic element combines with oxygen, the oxide formed is usually gaseous. If the gas is combined with water, then an acid is formed.

Bases and Alkalis 7.38
When a metallic element combines with oxygen it forms an oxide. If an oxide reacts with an acid and forms a salt, it is called a base. If the base is soluble in water, it is called an alkali. Alkaline solutions contain hydroxide ions (H₃O⁺). They are electrolytes and will react with acids to form salts and water. This fact is of the greatest importance to our interior economy.

In all things you shall find everywhere the Acid and the Alcaly.
Otto Tachenius ‘Hipporates Chemicus 1670

Figure 7.38A

 

 

When acid and base are combined in the correct proportion, neutralization occurs and the product is a salt. The type of salt formed will obviously depend upon the type of reactants and the composition of the solvent.

Strong acids and bases result in a fast reaction time; with weak acids and bases, the reaction may be spread over a number of weeks, and therefore go unnoticed, which if alkaloidal salts were being precipitated in plant preparations and where the wrong solvent is used then, it could have serious and even tragic consequences

Buffer Action 7.39
The term buffer is used for certain salts that suppress the degree of acidity in relation to the actual acid content of a liquid. A buffer solution, is a solution whose pH is not greatly affected by small additions of an acid or alkali. There are two types of buffers commonly used.

1. A weak acid and its corresponding sodium salt.
2. A weak base and its salt with a strong acid.

Acidity and Alkalinity 7.40
A common method to determine whether a substance is acid or alkaline, is by the use of litmus paper. Litmus is a soluble powder obtained from lichens. It is also available in solution form. It is used merely as an indicator of acidity or alkalinity, it will not show the relative strength of either condition. It indicates the condition by a change in color. The litmus paper comes in two colors.

1. Red, which is used to test for an alkali, if the substance is alkaline the paper will turn blue.
2. Blue, which is used to test for acid, if the substance is acidic the paper will turn red.

If the paper does not change color the substance is neutral (pH7).

To indicate relative acid or alkali strength a universal indicator must be used. Universal indicators are available as paper strips or as solutions. The solutions will give a full spectrum of color changes, from red (acid) through to purple (alkaline). Each kit will contain a color matching chart which indicates the relative strength of the acid or alkaline condition.

The pH Scale 7.41
The acidity or alkalinity of a substance depends upon it concentration of hydrogen ions. The pH scale is based on the common negative logarithm the ‘p’ simply means the strength or power of the hydrogen ion concentration. For example, instead of saying that the pH of a substance is 7, we could say that the hydrogen ion concentration is 10^-7 moles per litre. However, it is more convenient to use the negative power. The mole concept will be dealt with later in the text.

 

Table 7.41A

 

A solution that rates zero on the above scale contains many hydrogen ions (H⁺) and few hydroxyl ions (OH^–), whereas one that rates 14 has many hydroxyl ions and few hydrogen ions.

A pH of 7 is neutral and contains one ten millionth (0.0000001) of a mole of hydrogen ions per litre.

A solution that has more H⁺ ions than OH ^– ions, is acid and will be below pH7 on the scale. A movement of 1 whole number on the scale represents a 10 fold change on the previous condition.

Strong acids and alkalis are corrosive and destructive of living tissue. Appropriate precautions should be taken when handling such substances.

Chemical Analysis 7.42
The chemical analysis of a substance involves; firstly the determination of what is present and secondly the determination of how much is present. What is present is called ‘Qualitative’ analysis. How much is present is called ‘Quantitative’ analysis. We are not much concerned with what is present because in Herbal work the identity of the natural substances employed will be known. The quantitative accuracy of the substances used is of prime importance when compounding or dispensing a medicinal substance.

Quantitative Chemistry 7.43

Quantitative measurements are of two types;

1. Volumetric measurements where the volume (usually gas or liquid) of the substance is expressed in litres or its sub-multiple the millilitre.

2. Gravimetric measurements that may apply to liquids or solids. A substance may be weighed, the unit of measurement is the kilogram or its sub-multiple, the gram.

Alternatively we can determine the density of a substance in which case we refer to it as having mass per unit quantity, i.e. as grams per cubic centimeter ( g/cm^³ ).

There is a third type of measurement that is concerned with the amount of matter in a substance, i.e., how many entities there are in a given quantity of any substance. The unit of measurement is the ‘mole’. Its symbol is ‘mol’ and its mass per unit quantity is expressed as mol/L, or kg/mol.

The Mole and Avogadro Constant, 7.44
Molar measurements, are a most useful tool for the Herbalist. An understanding of the mole concept will also clarify aspects of homeopathic pharmacy.
In 1811, the Italian physicist Count Amedeo Avogadro, published a hypothesis that went largely unnoticed by the scientific community for nearly 50 years.In brief, the paper suggested that equal volumes of any gas, under the same pressure and temperature, would contain the same number of particles. Subsequently, Avogadro’s hypothesis was developed as a core concept of physics and chemistry. The basic idea is that individual units are counted by weighing a given quantity, in the same way that a bank teller will weigh coins to determine their value.

One mole of any substance is its atomic mass number expressed in grams. This amount will contain as many ‘entities’ as there are atoms in 0.012 kg (12 grams) of Carbon 12, which is the standard mole. It will be seen from the Periodic Table, that the elements do not have simple whole numbers, due to the presence of naturally occurring isotopes. It is sufficiently accurate to use the simple whole numbers rounded, e.g. Carbon12, Oxygen16, Nitrogen14 and so on.

12 g of Carbon 12, which is the standard mole, contains;

6.02252 x 10²³ atoms.

This number is called ‘Avogadro’s constant’, or Avogadro’s number. Therefore 1 mole of oxygen weighs 16g and contains ;

6.02252 x 10²³ atoms.

Avogadro’s number is astronomical, and when written in full it is quite incomprehensible.

 602252 000 000 000 000 000 000.

Avogadro’s number is often cited by orthodoxy to refute the homeopathic claim that the serial dilution of a remedy will increase its potency.

According to Avogadro’s theory, when a serial dilution of 12c (centesimal) or 24x (decimal) has been attained, not a single molecule of the solute will remain in solution. Nonetheless, the enigma of homeopathy remains because undoubtedly high serial dilutions produce a very pronounced effect on a healthy person. Homeopathic pharmacy will be covered later in the text.

Molar Solutions, 7.45
A solution may be defined as a solvent, i.e. a liquid in which a substance called the ‘Solute’ is dissolved. A solution is homogeneous.

As stated, 1 mole of any substance is its atomic number expressed in grams, e.g. 1 mole of Hydrogen weighs 1 gram. And contains 6.02252 x 10²³ atoms.

1 mol of Oxygen weighs 16 grams. In the case of a molecular compound, the atomic mass numbers are added together; for example water; its molecular formula is H₂O and we wish to know the weight of 1 mol H₂O, proceed as follows;

Hydrogen atoms = 2 x 1 = 2g = 2 mol ‘H’
Oxygen atoms = 1 x 16 = 16g = 1 mol ‘O’
Total = 18g = 1 mol H₂O
Therefore, 1 mol H₂O weighs 18g and contains 6.02252 x 10²³ molecules.

1 mol of any compound is its formula weight in grams. The concentration of a solute in solution may be expressed in moles per litre (mol/L), or as grams per litre (g/L). For example, a 1 mol per litre (1mol/L) Saline solution, would contain 58g of Sodium chloride (NaCl) per litre, e.g. Na = Sodium = 23g/mol and Cl = Chlorine = 35g/mol. Total = 58g/mol which is expressed as 1 mole/L or 58g/L NaCl.

Density 7.46
Density is the measure of compactness or concentration of a substance and it is defined as its mass per unit volume.

To calculate the density of a substance, the mass (weight) is divided by its volume. If the substance is a solid the answer will be expressed in grams per cubic centimeter (g/cm³). If the substance is a liquid, in grams per millilitre (g/ml).

To calculate the density of a regular shaped solid, first weigh the sample, then calculate its volume. The weight is then divided by the volume. The formula is as follows;

Density = Mass ÷ Volume = g/cm³

For example; a substance weighs 75 grams and its volume is 8.6 cm³, therefore,

75 ÷ 86 = 0.872 g/cm³ or s.g. 0.872

 If the substance is a liquid, the calculation is the same, except the answer will be in grams per millilitre.

 
Relative Density 7.47
Relative density is commonly referred to as Specific Gravity or s.g. Specific gravity has the same numerical value as density, but has no units such as gram or millilitre. Instead distilled water, at a temperature of 20°C, is used as the standard, against which the relative density of the other substances are compared. 1 ml H2O at 20°C will weigh 1 gram. Distilled water is assigned the value of 1 and expressed as 1.000.

If you refer to Table 6.31A it will show that the weigh per unit quantity, of a given substance (g/cm3) has the same numerical value as relative density or s.g. Accordingly, we may define s.g. as a ratio of the weight of a volume of a substance, compared to an equal volume of distilled water. Or in another way, the number of times that a substance is heavier or lighter that water;

Alcohol 95% weighs 0.810 g/ml and its SG is 0.810 (at 20°)

Water weighs 1 g/ml and its SG is 1.000 (at 20°)

Glycerin BP weighs 1.260 g/ml and its SG is 1.260 (at 20°)

Temperature and Density 7.48
For the Apothecary the s.g. or density, of a given substance is of prime importance and from it much valuable information is obtained, for example the alcoholic strength of a solution of alcohol and water may be determined. If we know the alcoholic strength of a solvent we may calculate the amount of soluble extractive contained in a given volume. In the first instance, we can know if the solvent is of the correct strength for extraction or preservative purposes. In the second, we can know the amount of solute in the solution.

The density of a substance is a physical property which may be used for identification purposes with the proviso that the measurements, i.e., weight and volume are made at an agreed temperature and pressure.

Standard temperature and pressure (STP) for chemical work is usually 0°C at 1 atmosphere. 0°C, the freezing point of water is not a convenient temperature for routine tasks, which are usually carried out at room temperature. In the older official publications this was defined as 60°F or 15.56°C, however since the introduction of the international SI units the agreed standard is 20°C (68°F).

Metric measurements when given in a Pharmacopoeia are graduated at 20°C so there shall be no errors arising due to the expansion or contraction of solutions at other temperatures. This is particularly important when preparing hydro-alcoholic solvents which are specified for a particular substance.

Considerable heat is evolved when the dilute alcohols are prepared, in addition there may be a disparity between room and solution temperatures. Accordingly, the SG of the alcohols will be shown at 20°/20°. That means the solution at 20°C and the ambient (surrounding) temperature at 20°.

If measuring, by SG, a sample of alcohol and water at 20°C, we determine its alcoholic strength to be 14% by volume at 30°C. The same sample, due to expansion, would only contain 10.75% alcohol by volume. Alcometric and temperature correction tables will be supplied later in the text.

Percentage Solutions 7.49
The term percent is from the medieval Latin ‘per centum’ meaning ‘by the 100’ and in modern terms the proportion or rate per 100 parts. The symbol is ‘%’.In the context of Apothecary work the term ’percent’ will have one or four different meanings, only one of which is a true percentage compound due to differing weights and densities. The meanings and symbols are as follows;

1. The percentage weight in weight is the only true percentage compound, and it means the weight of solute in a solution, or weight of active ingredient in the product, e.g. 4% w/w of Symphytum extract in an ointment or solutution.

2. The percentage as a volume in volume. This is not a true percentage compound due to the different density and weights of the constituents, e.g. a hydro-alcoholic solvent, Alcohol 30% v/v, which means 30 ml of alcohol in 100 ml of product.

3. The percentage as weight in volume. Again, not a true percentage compound, and it means the weight of active ingredient dissolved in 100 ml of product, e.g. Sodium Chloride 3% w/v.

4. The percentage, volume in weight, meaning the volume as mls of active ingredient in 100 g of product, e.g. Calendula tincture 7.5% v/w which is not a true percentage compound.

Percentage Formulae 7.50

Occasionally formulae may be expressed as ‘parts’, for example;

Alcohol – 3

Water – 7

 This may mean: by volume, or by weight, in either case, the strength of the resulting solution would be different from each other, for example,

Table 7.50A

Substance	Parts	°C.	SG	Weight
Alcohol	3	20°	0.811	0.811 g/ml
Water	7	20°	1.000	1.000 g/ml

 

 

 

 

 

Table 7.50B

Substance	Parts	By Volume	By Weight	As Volume
Alcohol	3	3 ml	3 g	3.69 ml
Water	7	7 ml	7 g	7.00 ml
TOTALS	10 Parts	10 ml	10 gm	10.69 mls

Assuming that the alcohol is the active substance in the solution, then we may say that;

 3 as a percentage of 7 is 3 ÷7 = 42.8% alcohol in the solution by volume.

However, if we have compounded the solution by weight then the percentage of active substance is different, i.e.

 3.69 ÷ 7 = 52.7% alcohol. The difference is almost 10%, which is considerable.

Another example would be that the formula may be a combination of liquids and solids as follows;

Starch 1

Salt 10

Water 90

In all such formula the ingredients are weighed, with the exception of the water, because water weighs 1 gram per ml. The rectified formula would read as follows;

Starch 1g = 1% w/v

Salt 10g = 10% w/v

Water 90 ml = 90 ml

This is the method to be followed in the absence of specific instructions. As a further example the formula could be written as follows;

Starch 1% w/v

Salt 10% v/v

Water 90 ml.

It will be understood that formulae ‘A’ and ‘B’ differ in quantities because of the relative density, or s.g. of the substances. If formulation ‘B’ is intended, then it will be as such.

Percentage Composition 7.51

Formulae may sometimes be given by weight and we may wish to prepare a differing quantity to that shown, accordingly, the active ingredient should be determined as a percentage of the total preparation, e.g.

Acetic Acid 25 g

Distilled Water 500 g

In this instance, the acetic acid is the active ingredient and we proceed thus;

25 ÷ 500 x 100 = 5% of the total

As a further example, we may use the saline solution given in Section 7.45, i.e. 1 mole NaCl per litre = Common salt 58g. Distilled water 1000g.

Therefore 58 ÷ 1000 x 100 = 5.8% of the total.

Proportions and ratio’s 7.52
It is common practice to represent drug/solvent proportions as a ratio, i.e., a given number of milliliters will represent 1 part by weight of the drug. For example, the general rule for a ‘Tincture’ (There are exceptions) is that 4 ml of the fluid will represent 1 gram of the drug and has a ratio of 1 : 4. I feel this has more to do with convention rather than accuracy and that w/w would be the better measurement to use.

In the general methods adopted by the Pharmacist, for the standardization of tinctures and extracts, It is common practice to represent drug/solvent proportions as a ratio, i.e., a given number of milliliters will represent 1 part by weight of the drug. In the general methods adopted by the Apothecary for the standardization of tinctures and extracts, the use of ratios should be adhered to. Occasionally the formulae of medicinal substances are given in a variety of ways, e.g. common fractions or decimal fractions, and one must be able to manipulate the numbers to arrive at a desired.

Occasionally the formulae of medicinal substances are given in a variety of ways, e.g. common fractions or decimal fractions, and one must be able to manipulate the numbers to arrive at a desired term.

The percentage represented by a ratio is arrived at in the following manner, e.g. 1 : 4 = 1 ÷ 4 = 25%.

Decimal Numbers and Fractions 7.53
Decimal numbers have a base of 10. The number may be a whole number or a decimal fraction. To separate a whole number from a decimal fraction, the term decimal ‘point’ is used. All numbers to the left of a decimal point are whole numbers, and to the right, fractions. For any number less than 1, it is the custom to place a zero to the left of the decimal point thus avoiding gross error if the point is omitted.

Reading Decimal Numbers 7.54

Table 7.54A

Whole Numbers.	Decimal Numbers.	Decimal Fractions.
Units	1	Tenths
Tens	2	Hundredths
Hundreds	3	Thousandths
Thousands	4	Ten Thousandths
Ten Thousands	5	Hundred Thousandths
Hundred Thousands	6	Millionths
Millions	7	Ten Millionths

 

Multiplying and Dividing Decimal Numbers 7.55

When multiplying a decimal number by units of 10, simply move the decimal point to the right by the number of zeros that there are in the multiplying number, e.g.

0.5 x 10 = 5.0 0.5 x 100 = 50 0.5 x 1000 = 500

When dividing by units of 10, move the decimal point to the left by the number of zeros, e.g.

 0.5 ÷ 10 = 0.05 0.5 ÷ 100 = 0.005 0.5 ÷ 1000 = 0.0005

 
Changing Percentages to Decimal Fractions 7.56
The denominator of a percentage is always 100. If the numerator is divided by the denominator the answer is the decimal fraction, e.g.

5% = 5/100 therefore 5 ÷ 100 =0.05

 20% = 20/100 ˆ 20 ÷ 100 = 0.20

 43% = 43/100 ˆ 43 ÷ 100 = 0.43

Changing Decimal Fractions to Percentages 7.57
A decimal fraction is converted to percentage simply by moving the decimal point to the right and substituting the percentage sign, e.g.

0.05 = 0.5% 0.20 = 20% 0.43 = 43%

Changing Percentages to Common Fractions 7.58

Remember that percentage means the proportion, or rate per 100 parts, therefore, when converting a percentage to a common fraction, 100 is always the denominator, and the numerator is the percentage under consideration, for example 5%.

Numerator 5 parts

Denominator 100 parts

The fraction is reduced to its lowest terms, that is when the only common factor between the numerator and denominator is 1, therefore, 5% is 1/20^th of 100.

Changing Percentage to Ratio 7.59
The numerator is always the first part of a ratio and the denominator is the second part, e.g. a 25% solution;
25% = 25/100 = a ratio of 25 : 100

The ratio is then reduced to its lowest terms;
100 ÷ 25 = 1 : 4

Changing Ratios to Percent 7.60
The ratio is first changed to a common fraction, then the fraction to percent, e.g.

1 : 4 = ¼ x 100 = 25 then add the % sign i.e., 25%.

 

Chapter 8

 

Library
Pharmageddon Herbal Block Index

 

 

Earth Air Fire and Water
The Pharmageddon Herbal
The Essential Distillation
Chapter 6 Part 2

Fractional Distillation 6.14
Fractional distillation is an old technique employed in the hermetic arts to separate the different components of a mixture. Separation may also be achieved by simple distillation, but the technique is discontinuous and can become tedious. Whereas the fractional technique is a continuous process that conserves time and energy.

Any fermented alcoholic liquid is a soup of bewildering molecular complexity, and when it is distilled then a myriad overlapping phenomena occur. Given the great variety of botanic materials which may be subjected to the fermentation process, understandably the fermentation products will be many, which produce a complex of vapor pressures.

Since water evaporation will occur at all temperatures, then the composition of the vapor arising from the heated liquid will be undergoing constant change, as the lower boiling point components distill off in sequence. In Herbology, the major use to which the technique is put, is for the fractional distillation of ethanol from an alcoholic mixture. However, for more advanced work, fractional distillation under reduced pressure may be used for certain of the perfume oils. Further information will be given under the heading of Essential Oils.

The preparation of ethanol, employing the simple distillation technique, will on condensation produce a liquid which contains some 50 to 60 % water, depending on the care taken. Water evaporates at all temperatures above 0°C and water vapor will be carried over with the ethanol.

The collected distillate must then be redistilled a number of times to free the ethanol from as much of the water as possible. Traditionally the old herbalists would distill the liquid seven times. (Spagyric work) However, by employing a fractional column, high strength ethanol may be produced in a single distillation. The principle involved is shown in the following Figure.

Industrial Fractionating Column. Figure 6.14A

If we have a fermented liquid that contains 10% by volume of alcohol and we commence to heat the liquid, then both water and alcohol will start to vaporize. The higher the ascent of the mixed vapor, the cooler it will become, consequently the vapor with the highest boiling point (in this case water) will start to condense in the fractionating column and run back into the body of the still. The vapors of the lower boiling point continue to ascend the column. In returning to the still, the condensed liquid will contact the rising vapors and a further heat exchange takes place, which further enriches the ascending vapor.

Small Scale Fractional Distillation. Figure 6.14B

There are various types of fractionating columns available. One of the cheapest and reasonably efficient is the so called ‘Hempel’ column, which is illustrated in Figure 6.14B.

It is essentially a hollow glass tube with a side arm. The tube is usually packed with a suitable material to within 1 cm of the side arm. The packing material should not react with, and allow free passage of the volatile vapours. Suitable material could pieces of glass tubing or small glass beads. If using beads, a small piece of mesh should be placed in the bottom of the column to hold the beads in place. I have found that stainless steel pot scourers cut up work very well.

Fractionating tubes may vary in length. If distilling a liquid where there is a considerable gap between the component boiling points, e.g., alcohol and water, then a relatively short column will suffice. If dealing with a liquid where component boiling points are close together, then a longer tube should be used.

Ideally the temperature of the column should be maintained at some 5 to 10°C below the boiling point of the liquid undergoing fractionation. In large scale equipment, a heating jacket is used. For smaller scale operations the tube may be lagged with cotton wool and held in place with domestic kitchen ties that are normally used to seal plastic bags.

Distillation in Steam 6.15
Steam distillation is a very useful technique and one that finds wide application in the extraction of essential oils from plant material. When distilling two immiscible liquids, the mixture will boil when the sum of the vapor pressure equals the atmospheric pressure. Accordingly, the mixture will boil at a lower temperature than the component with the lowest boiling point. Obviously this procedure is sparing on the delicate nature of the volatile oil molecules.

For example; the boiling point of Carvone at atmospheric pressure is approximately 230°C, its partial pressure at the boiling point of water is 9 mm Hg (9 torr). Therefore,

Water at 100°C = 760 mm Hg. Carvone at 100°C = 9 mm Hg. When mixed they boil at 751 mm Hg.

As shown in Figure 4.44A, the boiling point at that pressure approximates 99°C. In relation to the mass of a herb the yield of essential oil is small, therefore, except for analytic purposes, small laboratory scale equipment can be of good service use for small community Apothecary production. In the area of product development small scale equipment is an essential.

The basic laboratory process requires the herbal material to be suitably reduced in size. This will rupture the oil cells of the plant material and release volatiles to the air. To avoid losses the material must be transferred promptly to the flask and then injected with live steam. The volatile oils are then carried over to the condenser with the steam. The evolution of steam may be achieved by employing various methods.

Distillation in Steam 6.15A

The component marked ‘A’ is the steam generator. The cork or rubber bung is pierced by a hollow glass tube. The tube is the water level indicator. When steam issues from the tube. The heat is turned off and the steam generator may then be topped up. The side arm which is the steam injector may be dispensed with and replaced with a second glass rod through the cork or bung which can then be led to the boiling flask which is at ‘B’. If it is necessary to introduce heat to the bottom of the boiling flask at ‘B’ then the size reduced herbal material should be partially covered with water lest charring occur. In which case, the distillate will be contaminated with an empyreumatic (burnt) odor, rendering the distillate worthless. The condenser is at ‘C’ and the collecting flask at ‘D’.

Fabricated Domestic Still (multi-purpose) 6.15B

A. Breakable joints for cleaning purposes.

B. Clamps to hold the lid/head secure. The gasket should be made from cork or similar heat and vapor resistant material.

C. Basket made from stainless steel mesh.

D. Welded lugs to support the basket above the water.

E. Water space to generate the steam.

The still, as shown, is very basic but nonetheless versatile. By removing the basket it may be used for simple distillation of water or alcohol. A simple but effective fractionating column may be easily made from stainless steel tubing of a suitable diameter. The liquid level within the still may be determined by measurement of the amount of distillate in the receiver. That amount is subtracted from the original amount of water in the still. The refinements possible will be discussed in Section 6.17.

Distillation under Reduced Pressure 6.16
Distillation under reduced pressure is an extremely useful technique which has application in 2 major areas.

1. To minimize or prevent decomposition of a thermo-labile substance. When working with heat the thermal cracking of a herb’s molecular structure is an ever present possibility. The subsequent chemical change renders the material unsuitable for the purpose required. Some typical examples of undesirable changes are as follows;

A. Hydrolysis of Alkaloids or Glycosides. Both components are readily decomposed at temperatures exceeding 60°C.

B. All enzymes are inactivated or destroyed at temperatures exceeding 70°C, and in some cases at around 60°C. Fortunately this is a minor problem for the Herbologist, in that very few enzyme active substances are used. A notable exception would be Malt Extract, which must be concentrated at temperatures below 55°C.

C. There are numerous herbal preparations that contain or rely on the presence of Tannins for their medicinal effect, e.g., Hamamelis, Krameria, or Wild Cherry bark. Such plants contain tannins called ‘phlobatannins’. When heated at temperatures exceeding 60°C Phlobatannins are converted to insoluble compounds, known as phlobaphenes, which are then precipitated from solution.

D. Many alkaloids, when subjected to temperatures exceeding 90°C, will undergo a chemical change known as ‘Racemization’, whereby an optically active substance may be rendered optically inactive. The new substance will contain the same number and type of atoms but will differ in its structural arrangement, thereby altering or canceling its properties. Such structures are called ‘Isomers’. Chemical concepts will be covered in the next module.

2. The second major use is to influence the physical form of dry extracts, for the purpose of facilitating the production of granular powders. If a liquid extract is reduced by evaporation to a honey like consistency under atmospheric pressure and then placed under reduced pressure, a sudden evolution of water vapor is induced causing the extract to expand suddenly. The result is a light friable mass which is easily reduced to a granular powder by rubbing through an appropriate sized sieve. The manufacture of extracts will be covered later in the course.

As previously discussed, if atmospheric pressure above a liquid is reduced, then the boiling point of the liquid is also reduced in line with the pressure. Figure 4.44A illustrates the point.

The atmospheric pressure is reduced by means of a vacuum pump. For small scale operations, a suitable pump may be obtained from a laboratory supply company. For production scale operations, an adequate second hand pump may be purchased from a dealer in dairy milking equipment. Such pumps will produce a partial vacuum of 50 kPa or around 350 mm Hg.

The point at which the pump is linked to the apparatus is of importance if equipment is to operate correctly. The following drawing illustrates the usual arrangement of the individual components.

Distillation under Reduced Pressure. Figure 6.16A

All joints must be airtight. If using ground glass joints, then a very light smear of petroleum jelly will be required.

A liquid, when boiled in a closed flask, will quite often generate a condition known as ‘Bumping’. Vapor is released in large bubbles instead of a steady stream of smaller ones. That situation is avoided by the introduction of boiling chips, or granules, to the flask. This allows the formation of many small vapor bubbles which are released in a steady stream.

Under reduced pressure the bumping can be very violent accompanied by splashing and frothing of the liquid. In such cases the boiling chips are inadequate. The problem is circumvented by the introduction of an air leak tube to the flask, as illustrated in Figure 6.16A.

The air leak may be constructed of a glass capillary tube fitted with a sleeve of a rubber tube. The rubber tube is sealed with an adjustable clamp. If the bumping commences, the clamp is opened slightly to allow a fine stream of air bubbles through the liquid. This may be done without unduly affecting the vacuum system.

Safety Precautions 6.17
When starting to work with reduced pressure systems, it is advisable to remember that under a partial vacuum of 0.5 of an atmosphere, that each cm² of the surface of the vessel carries a weight of 0.5kg, which increases as the pressure reduces. Glass vessels, unless specially strengthened may implode with all of the consequent dangers. Glassware for vacuum work may be purchased from laboratory supply houses. Think about what you do …… before you do it !

A Simple Vacuum Pump and Manometer 6.18
A simple but effective pump, for small scale vacuum work, is the water jet pump, sometimes called a ‘venturi tube’. The pump is simply connected to a water tap that operates at mains pressure or around 100 kPa. The water jet pump is quite efficient and with the proviso that the system is airtight, and the mains pressure remains constant, then the vacuum attained will correspond to the vapor pressure of water for a given temperature. The vapor pressures shown in Table 6.18A may be read in mm Hg or in torr (1 torr =1 mm Hg).

Vapour Pressure of Water. Table 6.18A

Temperature °C	Vapour Pressure
5	6.5
10	9.2
15	12.7
20	17.5
25	23.7
50	92.5
100	760

Water jet vacuum pumps, are usually constructed of non ferrous metal and sometimes of glass, with varying degrees of sophistication. However, the principle of operation is simple and an adequate pump may be constructed from metal or glass tubing.

Water Jet Vacuum Pump. Figure 6.18A

For various reasons when working with reduced pressure, there is the ever present possibility of contamination, due to suck back caused by leakage in the apparatus. Therefore, it is common practice to place a trap between the pump and the apparatus, so that if the pressure is equalized, contamination will not occur.

A Simple Trap. Figure 6.18B

The flask as shown is the ‘Buchner’ or filter flask. The Buchner flask is strengthened to facilitate filtration at reduced pressure.

On completion of the distillation procedure the heat should be turned off and the pressure equalized gently by slowly opening the vacuum release cock on the contamination trap, after which the pump may be shut down.

A useful addition to the laboratory equipment for small scale work is the manometer which is an instrument used to measure the pressure of a liquid, gas or vapor. They are simple and easily constructed.

 

The Manometer. Figure 6.18C

A wooden meter rule is cut at the bottom at the 800 mm line and inverted so that the 760-mm line can be zeroed at the level of mercury in the reservoir. When the apparatus is subjected to a vacuum, the pressure may be read directly from the rule in torr or mm Hg. Ensure that the glass tube and reservoir are of sufficient strength to withstand the reduction in pressure.

For production scale work the manometer is replaced by a vacuum gauge. The herbologist employs low pressure techniques in two areas. The first being in the concentration of the plant extracts and secondly in the production, or separation of essential oils from the material, where that material is of a delicate nature; otherwise, steam distillation is the method used.

In regard to the concentration of extracts, the solvents involved are water and ethanol. Therefore, with the proviso that the apparatus does not leak, then the manometer may be dispensed with. The boiling point (bp) of water and ethanol are known. By comparing the temperature at which boiling commences, with the vapor pressure curves in Figure 4.44A, the degree of vacuum may be known.

Production Scale Equipment 6.19
With consideration given to those points raised in Sections 6.3 and 6.4, simple or sophisticated production plant may be manufactured from second hand materials for a modest outlay. As previously mentioned 2^nd hand dairy equipment may be easily adapted to suit the purpose.

If you can locate a small, owner operated, engineering shop, then the simple diagrams that follow will allow you to dispense with expensive technical drawings. My personal experience of such establishments, has always yielded expert advice and innovative solutions for tight budgets.

When seeking used equipment, the first requirement is for vats and containers. Remember that holes can be patched and fittings removed or modified. Containers and vats may be found from 20 to 4,000 litre capacities. If dealing with liquids, then remember that a batch production will be around 30% less than the nominal tank capacity.

When dealing with a solid, such as fresh or dried herb, then a batch load will be considerably less than the capacity of the tank or vat. As a rough rule for fresh herb; the weight of the herb in kg is circa 12 to 18%, (depending on the material), of the tank capacity in litres. If operating on dehydrated material, then that percentage will increase to 25 to 30%.

The second requirement is for stainless steel pipe and tubing of various diameters. Check to ensure that the bores are not contaminated with scale. If it is, do not be tempted to purchase.

Finally fittings, such as breakable joints, taps, stopcocks, one way valves and sight glasses, will present considerable savings on the price of new.

The text contains sufficient information for you to arrive at a reasonable estimate of water and fuel needs to meet production requirements. Do not be too ambitious and think the whole process through, then commit it to paper, before spending money.

Involve yourself at every stage of plant construction, in that way, you will learn how to service and repair your own plant.

When operating the plant, strict attention to the cleanliness of the equipment must be observed, lest cross contamination occurs. Tubes and pipes must be cleaned with brushes. Spiral coil condensers should have steam passed through them for 30 minutes. For small scale equipment items may be sterilized for 15 minutes in a domestic pressure cooker.

The Multipurpose Still. Figure 6.19A

 

Notes to the Multi-Purpose Still 6.20
The production sized still should take account of the physics involved and as previously covered. The still as shown in Figure 6.19A is set up for the steam distillation of essential oils.

The herb to undergo oil extraction is suspended in the charge basket above boiling water. The steam generated passes though the herb, carrying the volatile oils to the condenser.

The Florentine receiver automatically separates the oil from the condensate. The watery condensate is milky in appearance, which is due to very finely dispersed particles of oil, that it contains. The condensate is also automatically fed back to the still, where it will undergo the distillation cycle again, thereby increasing the overall yield of oil.

For the preparation of distilled water, the charge basket is removed and the condensate return vent is replaced with a constant level device, (see Figure 6.7B). The Florentine receiver is removed and the oil receiver is connected to the condenser.

The arrangement for the ethanol is the same as for distilled water, however, the condensate return vent tap must be turned to the ‘off’ position, to prevent loss of the solvent.

The breather tube on the oil receiver may be used to attach a vacuum pump for any operation that requires low pressure. The still must be made air tight by turning off all inlets that may have contact with the vacuum system.

The still must be thoroughly cleansed after use and if used multipurpose, the following rotation is recommended;

Water – Essential Oils – Ethanol – Water

This will minimize any potential for cross contamination.

For the fractional distillation of ethanol, the expansion head may be packed with stainless steel scourers to within 5 cm of the bend in the head. The expansion head must be adequately lagged (insulated) to prevent undue refluxing of the ethanol. The subject of refluxing will be covered later in the text.

The still may be bottom fired by means of a simple solid fuel block built furnace, upon which the still would stand. A 6mm steel plate must be interposed between the heat source and the still bottom.

The still head and charge basket will need to be removed and replaced with a block and tackle, the still is serviced from a raised platform.

Distillation apparatus is designed for many different purposes in varying degrees of sophistication, with an ascending scale of cost. For pharmaceutical purposes is usually constructed to withstand a steam pressure of 2 kg/cm² (approximately 30psi).

However, such equipment is expensive, and for obvious reasons, steam safety regulations must be complied with. The operator of high pressure steam equipment will, in all probability, require a steam permit.

The Sublimation and the Distillation of Solids 6.21
During the first three decades of the 20th century, the products of destructive distillation (Pyrolysis) were official in the pharmacopeias of many nations, e.g., coal tar, birch tar and pine tar, more commonly known as Stockholm tar. Strictly speaking such substances are the products of distillation, in that the vapor phase passes to liquid, rather than directly to a solid.

The solid substance was enclosed, usually, in a cast iron pot, which was then subjected to a high heat that slowly charred the contents. The vapors from the resulting liquids were led away to be condensed on a cool surface, leaving a carbon residue in the pot. The phase changes are represented as follows;

Solid —> Liquid —> Vapor —> Liquid —> Solid

On further cooling the liquid assumes the familiar semi soft form. True sublimation does not pass through a liquid phase, i.e.

Solid —> Vapor —> Solid

The substances evolved from such processes are of little interest to the Herbologist, however, there is another variation on the above, which is as follows;

Solid —> Liquid —> Vapor —> Solid

The process is utilized to sublime benzoic acid from a base of gum benzoin. The benzoic acid is used as a bactericide for the preservation of various herbal preparations. Traditionally powdered gum benzoin or tincture of benzoin, were used for such purposes. Powdered gum is not recommended, due to various contaminants found in the raw gum such as insect parts and bark. The benzoic acid may be conveniently sublimed on the small scale in the following manner.

The Sublimation of Benzoic Acid. Figure 6.21A

Coarsely powdered gum benzoin is placed in the Pyrex dish; the dish is them covered with perforated filter paper, which serves as a filter trap for unwanted volatiles, this is then topped with the vapor condenser, as illustrated. The sand bath should not be allowed to exceed a temperature of 130°C.

The benzoic acid will form on the surface of the condenser, as white or very pale yellow, shiny crystals. Gum benzoin will melt around 120°C, depending on its origin and degree of purity, and boil at 249°C.

 

Chapter 7

Library
Pharmageddon Herbal Block Index

 

Earth Air Fire and Water
The Pharmageddon Herbal
Ivor Hughes
Chapter 10A
The Extractions

Introduction
Yet it happens that many herbs grow without having been sown, and these are often the best. There are also many important species that are better than those that are sown. Such is the power of the earth, and such is the power of nature; they do not rest. Therefore give heed to your inner garden, and also to yourself that you may learn that which no one can teach you, and which will amaze everyone.
Paracelsus.

Paracelsus was without doubt, the Father of Western Bio-Chemistry. He stated that life was a Chemical reaction. This nearly 500 years ago. From the greatest far flung Galaxies … to the Virus seed of life … that is an observable fact. When we exhale, or draw breath, it is a chemical act. When we eat and excrete, it is a chemical act. Molecules forming, breaking and reforming, and transmuting the elements. All at dazzling speed and low temperatures, the reactions flaring and subsiding like meteors flashing across a night sky.

The remedy is nothing but a seed, which you must develop;
Into that which it is destined to be.
Paracelsus
Man and His Body.

Disease or in its original understanding of the word, Dis-Ease, gives a pithy understanding, that covers a mild headache through the almost unendurable, nerve breaking pain. It is core concept that we are made from the elements of earth passing through many levels of being, rather like the many stages of becoming a butterfly. Or a bud becoming an apple. Such is the power of Nature.

Everywhere we look in nature, from micro to macro, we may see magnificent order. When all is in balance … when the metabolism … anabolic and catabolic, are at equilibrium … then order is maintained. It is well recorded, that residents of areas which are deficient in some trace element suffer from various types of metabolic disorders caused by an imbalance.

Further, those dis-orders may be corrected by making good the deficiency. For example iodine in salt. Sea salt is best. Our bodies have an affinity for it. Paracelsus was Physician for the Fugger Mining Company, and made a first hand study of the diseases that those miners suffered from. This in category of ore or metal that was being mined.

Each of the different organ systems of the body, are ordered by the glandular system, and its secretions. A deficiency of vital, bio-chelated (passed through a plant) trace elements, will lead to a malfunction of the organ systems involved, this at the cellular level.

Nature is not concerned with clinical trials, and inadequate statistical verification. Synergy simply means, right amount, in the right place …… at the right time. Nature has solved that problem nicely and delivered the goods in gift wrapping. Which we remove, and store the contents for further use. It only remains to select the remedy, and determine the dose …. Or is it ?

Spagyric Pharmacy would say, definitely not. For the reason … that the Galenic extract, is incomplete … it is minus the plant cell salts. Those salts are vital to the correct functioning of the remedy. The plant cell salts will make good, any deficiency, of those salts, within the cellular structure of the organ system, for which the remedy is intended. Thereby ensuring, correct organ, and related organ response. This type of response is a synergistic response.

The reason … the plant cell salts are the same as human cell salts. The plant has already done the work, the human cell does not have to put the salts through a production process before assimilation. The physiologic response when taken on an empty stomach is swift. The speed of assimilation may be modified, by taking the remedy with food, or after food.

The art and use of extractions is very old, lost millennia. Rinsing clothes in a brook is an extraction process. A vegetable soup is a decoction of vegetables. A sweat lodge or a sauna are extraction processes. Then slowly as the age of stone declined and the knowledge of metals seeped through the peoples ….. little seed pearls …. perhaps dropped at a shelter on an old trade route. Then the technology improved, as the metals extended our reach. Today, just as then, we have access to all manner of fine things. Healing Medicines. Food flavourings, inks, dyes, cosmetics and perfumes, fumigants and antiseptics.

-::-::-

The Types of Extract 10.1 The base form of all extracts is liquid and are classified into types as follows; A. The Liquid Extract is the strongest type of plant liquid made, its ratio of the plant material to solvent is 1:1, i.e., 1 gram crude drug represents 1 ml of the liquid extract. For technical reasons it may only be further concentrated by evaporation of the solvent. Occasionally a 1:2 preparation, i.e., 1 g crude drug equals 2 ml liquid is called an extract, this is incorrect and leads to confusion. When the term extract is used in this text, it means a 1:1 preparation. B. The Tincture is the most common form of plant liquid. An official definition of a tincture is that it has a drug/solvent ratio of 1:4 and that the solvent be a minimum 45% by volume. There are some difficulties with that definition because there are strong tinctures, i.e., 1:2 or 1:3 or they may go from 1:5 through 1:10. International protocol on potent plant drugs, e.g., Belladonna, Digitalis, Strophanthus etc. is agreed upon 1:10. The international protocol was established for obvious reasons. Preparations above 1:10 are little more than preserved concentrated infusions that will be covered later in the text. C. The Essential Oils represent a fraction of 1% of the total plant constituents and are not representative of a plant’s therapeutic range. They are undoubtedly the finest of natural antibiotics, which because of their potency can be dangerous in the wrong hands. If taken internally they can be extremely toxic, and if used without dilution externally, damage to the tissue can result.

D. The Expressed Plant Juices enjoyed a vogue in the early years of the 20th century but were gradually abandoned because of their limitations. They are brisk and vigorous in action, which may be attributed to the live enzyme content and as such, bear comparison with fresh fruit and vegetable juices. Not the least of these problems are those pertaining to dose (Posology) restraints must be adopted otherwise harm may result. The preserved juices are problematical. E. The Concentrated Infusions and Decoctions are prepared with water as the solvent. If taken in that form they are classed as recentium (recent) or alternatively they are preserved with alcohol 20%. F. The Pasty or Dry Extracts are prepared from liquid extracts by evaporation. They must be prepared with extreme care lest irremediable damage occurs. There are three types;

(1) Soft. (2) Semi-soft. (3) Dry. They are the basis of pills and ointments.

Methods of Preparations, Table 10.1A

Procedure	A..	B.	C.	D.	E.	F.
Pressure			X	X
Solvents.	X	X			X	X
Distillation			X
Pulverizing				X
Evaporation						X

Extraction Procedures 10.2
The term ‘menstruum’ is interchangeable with the term ‘solvent’. The term ‘marc’ in a general sense means the exhausted crude drug and therefore will also contain any other insoluble residue such as the proteins, e.g., albumins and globulins. The procedures for the extraction of crude drugs will with minor variations conform to the following procedures;

Table 10.2A

The procedures shown are in the order of the required operation.

Authentication of Crude Drugs 10.3
The commerce in crude drugs is a significant item of global trade. Crude drugs are exported to and imported from every continent. At source they may originate as a product of cultivation, or be harvested from the wild. In the crude state they are represented by all parts of the vegetable kingdom. Woods, barks, seeds, buds, flowers, leaves, whole plants.

As a pre-treatment, items of awkward shape may be coarsely chopped, lightly crushed or finely ground, to reduce the volume for packing and shipment. In other instances the crude products are essential oils, gums, resins and a variety of inspissated juices (made thick by evaporation) such as aloes.

Many of the products involved are traded on the world commodity markets, notably New York, London, Amsterdam, Hamburg and Tokyo. As such they are items of financial speculation and may be held in warehouses for up to four years in less than ideal conditions.

If items are products of cultivation, there is also the very real problem of heavy metal and toxic spray contamination from the cultivation regime. Many substances used are systemic, i.e., absorbed by the plants.

This is not such a concern if the materials are wild crafted, however all such products, if they cross national borders, will need a phyto-sanitary certificate. A certificate will not be issued without proof that the shipment has been irradiated or fumigated.

The fumigation procedure is carried out with toxic gases, residues of which, remain on the treated materials. However of even greater concern because detection is either difficult/expensive or not possible, is the use of gamma rays to irradiate biological products.

Herbs and spices are among the very few products that may be legally irradiated. The danger of gamma ray irradiation lies not in the radiation but in the molecular changes that occur in the bio-substances subjected to the treatment.

There is research evidence that suggests that the changes are implicated in the onset of degenerative disease in humans and animals that ingest such substances. Finally there is the age-old problem of adulteration and substitution of materials. These potential problems may be avoided by dealing with known organic growers or trading companies. Obviously this is not always possible, however a reputable supplier can provide a history of the materials sold. The minimum information required is as follows.

                                1. How old is the material, i.e., month and year.
                                2. Is it cultivated or wild crafted, i.e., sprayed or organic.
                                3. What is its country of origin.
                                4. How and at what temperature was the material dried?

Sampling of Crude Drugs 10.4
Scrutinizing a large batch of a crude drug in its entirety, is not feasible. However, it is necessary to have a system of sampling which will give a reasonably accurate picture of a batch condition and quality. The following method, with some small variations is that which is employed by all of the large drug houses. By adopting and adapting it for your own requirements, the accuracy achieved will meet most requirements.

When receiving a consignment of crude drugs they may be re-packs, the original packs have undergone a cleaning and grading process. After this they may be re packed, either into packs of the same weight as the original, or the bulk may be split into more convenient weights for onward sale. For example a shipper or major drug house would be more likely to offer the goods in the original pack size, e.g., 80 kg, 50 kg, 25 kg, etc. Whereas a wholesaler who supplies to retail trade will break bulk, e.g., 5 kg, 1 kg, 500g.

Original Packs and Repacks 10.5
To sample original packs you will need a core sampler. This device is similar to the domestic apple corer but much larger. For pack sizes from 100 kg to 25 kg a sample should not be less than 250g per pack.

The core sample should first be taken vertically through the sack, then horizontally, ensuring that the sample is from the central area of the pack. For packs from 20 kg to 5 kg the sample should not be less than 500g for the total.

Sampling Small Packs 10.6
For packs of 4 kg and under a sample should consist of not less than 25% of the total weight of the pack. This is done by hand and the sample weighed

Sampling Irregular Pieces 10.7
Core samplers are only of use if the crude drug is powdered or in pieces of 10 mm or less, e.g., seeds, powders or rubbed herb. Roots, rhizomes, stalks, leaves and petals are sampled by hand with the sample being taken from the core of the pack.

The Representative and Official Samples 10.8
For recording purposes the sample taken thus far is the representative (of the batch) sample. From this, the official sample is taken.

If the product is to be consumed, or used by another individual, the producer has legal as well as ethical obligations relating to the product. If there are problems arising down the line then you will need to justify your procedures. In practice this means, that your official sample, and the procedures followed, and your report on the sample, must be stored for a minimum of 12 months, and be made available upon official request. It is the responsibility of the individual to ensure that their procedures comply with the law that prevails, in the country from which they operate.

The official sample must weigh not less than 125g, this being the smallest amount required for official test protocols. Accordingly the representative sample should not be less than 1 kg if the official procedures are to be followed. Obviously there will be occasions when for various reasons that quantity will not be available. Therefore, the official procedure must be modified. The reason for modification should be stated in the report.

Let us assume a representative sample of 1 kg. The sample is thoroughly mixed and then spread out on a clean surface and then quartered. Two diagonal quarters are retained and two rejected. The retained quarters are again thoroughly mixed, laid out and quartered. Again two diagonals are retained and two rejected. The remaining 2 quarters comprise the ‘official’ sample or 250g of the original 1 kg.

The Physical Examination of Samples 10.9
The physical examination should be carried out in daylight and with the assistance of a hand lense. The first procedure is an organoleptic assessment of the material, write your impressions into the report, e.g., what is the color, is it bright, dull, etc. How does it smell? How does it feel, crisp or damp? Is it characteristic of the material?

Now spread the material on a white flat surface and scrutinize it with the lense; is there any obvious admixture of a different type or part of a plant? If so then try to separate it out. Normally this must be done by hand, but the use of a small spatula will make the task easier. If foreign plant material is present, separate it out and carefully weigh it.

Next examine the remaining sample for other adulterants such as insect parts, rodent or avian excreta, stones, etc. Then carefully weigh the remaining cleaned sample. Finally determine the percentage of the foreign plant material relative to the cleaned sample, for example;
 

   Original sample 250g.
          Foreign plant material 3g.
Foreign material 1g.
  Cleaned sample 246g.
Therefore:  3 divided by  246 x 100 = 1.22%

The upper limit for foreign organic material is 2%. If the sample is above that level, it must be discarded. Next determine the percentage of foreign material present as it relates to the whole sample;

Therefore:  1 divided by  249 x 100 = 0.4%

That figure is 40g/kg therefore the material will need to be further cleaned before extraction procedures are commenced. On the assumption that the material meets the other organoleptic criteria, it is then prepared for the extraction process.

Other Test Procedures 10.10
Regarding those matters discussed in Paragraph 10.3 it will be realized that materials sourced from growers, within ones own national borders, allow the Herbologist greater control of the materials handled. Contact with a grower that employs organic cultivation methods will render unnecessary any further analytic testing. Remember that only the arbitrary standardization procedure is used, therefore only a brief discussion of those tests will be given. A more detailed coverage of test protocols will be found in the appendices of the National Pharmacopeias and in particular those of the European Pharmacopoeia. These type of publications for most countries, will be available via the public library network

Analytic Protocols 10.11
Herbs and spices have always loomed large in human food behavior. With the turn of the 20^th century came large scale food processing and preservation methods that of necessity had to resort to herbs and spices for flavor and preservation purposes. Consequently there have been many attempts at setting universally applied standards that have so far only met with limited success due to the number of variables involved and the nature of the material.

The Tests 10.12
The tests are both qualitative and quantitative. If we talk of analysis, we mean all those tests involved in the qualitative and quantitative procedures.

If we talk of an assay we mean a truncated version of the total, i.e., those procedures carried out in a laboratory and are mainly concerned with quantitative aspects, i.e., ‘ how much is present’ of a given substance.

The results can be used as a ‘Guesstimate’ as to whether the plant is what it claims to be, and that it meets a given quality criteria, i.e., the levels of given substances fall within certain limits, similar to a human blood or urine test.

It must be clearly understood that ‘biological idiosyncrasy’ allows for no absolutes so that even if a given substance is under or over predetermined limits that no dogmatic statement can be made as to efficacy of a plant. We can only say ‘that based on probability’ the plant will, or will not reach a set standard of performance.

The procedures used are a combination of gravimetric and volumetric techniques. The techniques are either classic or instrumental. In the late 20^th and early 21st century, instrumental analysis is the norm, i.e., the procedures may be carried out by technicians rather than a chemists, however both methods are based on gravimetric and volumetric techniques. As a general rule, the tests employed are as follow;

1. Macroscopic and Microscopic Examination. Traditionally these procedures fall under the head of Pharmacognosy, and the histological characteristics of the plant are examined, e.g. for roots, the size and shape of starch grains, are of importance. For leaves, the number and size of stomas are examined. The sampling procedure is as previously covered. Full details may be found in a standard text.

2. Loss of Moisture on Drying. These procedures are usually carried out on previously dried material. Equilibrium moisture content has been covered in the Module dealing with Dehydration. If the material is obviously damp then it will be above equilibrium moisture content and should be considered unfit for use. Undoubtedly it will yield a high plate count of microorganisms and catabolic enzyme activity will be in progress.

3. The Ash Tests are of two types. The first is the total ash found after calcination of the plant and the second is derived from the first. The total ash is treated with hydrochloric acid. The residue remaining is the ‘Ash Insoluble in Hydrochloric Acid’. The tests are used to find in what quantities, elements are present, therefore they can be used for heavy metal contamination tests.

4. Water Soluble Extractive. Extractive tests are based on the solubilities of the various menstruum employed and will yield qualitative and quantitative information on the plant under tests.

5. Ethanol Soluble Extractive. The remarks for water also apply here.

6. Ethanol Insoluble Extractive. This usually refers to precipitated residues such as albumins and globulins etc. They are separated by filtration then dried and weighed, the percentage calculated against the air-dried drug.

7. Volatile Oil Content. This test is a sophisticated micro version of the far larger commercial operation. The results are calculated as milliliter of oil per 100g of the drug. The test may be used to produce oil for other types of testing, e.g., fractional etc. and is also used as a quantitative procedure.

8. Analysis of Active Constituents. The analysis of plant material can be carried out in one of two ways; the first is classical analysis.

The object of an assay is called the ‘analyte’. The methods involve quantitative methods, e.g. gravimetric or volumetric measurements, specific gravity and pH measurements. The qualitative assay is carried out by inducing a chemical reaction or a series of reactions between the analyte and another chemical or a mixture of chemicals called ‘reagents’. The reaction may be seen either as a liberation of a gas, the deposit of a precipitate or a color change.

The second method is instrumental analysis, by which many tasks are rendered routine and downgraded to technician level, thus freeing up the chemist for more rewarding tasks.

Instrumental methods employ both quantitative and qualitative techniques. Also important in plant analysis is the spectral and separation methods employed in chromatography.

Crude Reagent Tests 10.13
Nowadays there is a greater appreciation by natural science, of the synergistic effect of a total plant complex and not so much emphasis is placed on an isolated ‘active principle’ because every plant, whether it has recognized medicinal properties or not, will exert a physiological effect to a greater or lesser extent if ingested.

Total analysis, if it is possible, will be both lengthy and expensive and may involve the services of 2 or 3 skilled chemists. Consequently much plant material that passes through pharmaceutical company laboratories has only received a crude perfunctory screening in field conditions to decide whether or not, to investigate further.

The field or bench test usually centers on a probe for a particular type of constituent or functional group, e.g., alkaloids or glycosides. These simple tests do no more, than indicate the presence or otherwise of the group in question. Plants do not contain, in isolation, single alkaloids or glycosides. If they are present they will be so as a complex of different types. It is quite simply a matter of adding a specific reagent which is known to react with a particular functional group and observing the change, if any.

A Simple Test for Alkaloids 10.14
The test may be carried out on fresh or dried material. If the material is dried it should first be moistened with 25% dilute alcohol and allowed to swell, then proceed as follows;

Use a mortar and pestle and reduce 3 to 4g of the material to a paste using sufficient 25% alcohol to do so. If the material is fresh add a little clean washed sand to the mortar to help in making the paste. Smear the paste onto a clean filter paper and allow it to dry. Remove the dried paste and treat the stained filter paper with Dragendorff’s reagent. Dragendorff’s reagent (solution of potassium bismuth iodide) gives an orange coloured stain when alkaloids are present.

Testing for Glycosides 10.15
The simple test for alkaloids may be employed in a similar manner for glycosides. When the filter paper is dry, remove the paste, then add a few drops of antimony chloride to the paper and warm it gently over a light bulb. If the spot turns brown, it denotes the presence of cardiac saponins. If they turn purple, it denotes the presence of cardiac glycosides. The glycosides are notoriously unstable, and will be quickly broken down by enzyme action or by water (hydrolysis). The living plant arranges matters to suit its own economy and enzymes that hydrolyze glycosides are kept separate within the body of the plant. Therefore the value of alcohol as a solvent cannot be overstated in that it inactivates enzymes, and prevents hydrolysis. Indeed in this simple test all we reveal is the breakdown product of glycosides.

The Principles of Size Reduction 10.16
The methods of size reduction (comminution) and the sieves employed in the classification of particles obtained are treated in a previous module. A major factor in the solubility of a substance is the amount of surface area exposed to a solvent. The greater the exposed surface, the faster and more complete is its entry into solution, e.g.,

Surface Area. Figure 10.16A
The cube has 6 sides each side is 100 cm²
Therefore:  area exposed is 6 x 100 cm² = 600 cm².

We slice the cube into 8 equal portions.

The surface area for each cube is 6x 25 cm² = 150 cm²
Therefore:  8x 150 cm² = 1200 cm²

We have doubled the surface area. The degree of comminution required will also depend on the composition of the crude drug, e.g., is it hard or soft? Is it thick or thin? If the drug is leaf or petal then it will be easily penetrated by the solvent, therefore the degree of comminution need not be great, whereas hard and woody substances will require a greater reduction in size. Some substances such as aloes or gum resins need only be crushed, and it is a matter of becoming familiar with the material being operated on.

 

 

The following categories will serve as a general guide.

1. Broken or Crushed. Gums, resins and inspissated juices. Most seeds and fruits.

2. Sliced or Small Cut. Rinds, skins, pith, stalks.

3. Rasped. This type of size reduction is of dubious value and is only officially used for quassia that is a hard wood. From personal experience the tedium may be avoided by pulverizing such substances.

4. Powders. Rhizomes, roots, barks, woods, corms. There are 5 official grades of powder.  …………………….

……………………………………………………………………………………………………………………………………………………

 

Table 10.16A

For extraction purposes we may ignore the 80 and 120 mesh with the 25 and 45 mesh being most often used.

The final consideration for the degree of comminution needed, is the menstruum or solvent to be used for the extraction. Remember that our solvents are water, alcohol or a combination, i.e. dilute alcohol.

The tissue of crude drugs in the dried state will contain around 4 to 5% moisture if it has been properly conditioned, therefore if water or a dilute alcohol is used as the menstruum it will penetrate and spread rapidly through the plant tissue; whereas strong alcohol, i.e. 50% by volume or over in the initial stages will cause shrinkage or hardening of the tissue because the water is pulled to the surface thus shrinking the interior. This phenomenon may be explained by the fact that ethanol molecules have s hydrophilic (water loving) tail, i.e.,

The hydroxyl group is electrovalent (polar) and will attract water.

Water is also a polar molecule, and its oxygen atom will be attracted to the hydroxyl tail on the ethanol. The result is a slower diffusion of solvent through the tissue. Having regard to the general Table of Solubilities 8.50A our choice of menstruum is constrained by the chemical composition of the crude drug, for example it is pointless to attempt to extract resins with 25% alcohol. Accordingly as a rule, we can say that the greater the alcoholic strength of the menstruum, the finer the division of the crude drug. In practice this means that all substances that require a menstruum of 45% alcohol and over will need to be graded through a 45-mesh sieve. For menstruum’s below that strength, then 25 and 18 mesh sieves will serve the purpose due to the rapid diffusion of water through the substance.

The Extraction Process, 10.17
There are seven extraction processes in general use. They are;

Table 10.17A

1.	Infusion.	Water
2.	Decoction	Water
3.	Maceration.	Alcohol. Oils/Water
4.	Percolation.	Alcohol.
5.	Macero – Percolation.	Alcohol.
6.	Continuous Hot Extraction.	Water – Salts only.
7.	Distillation.	Steam and/or water.

Each process will be dealt with in turn. The infusions and decoctions are no longer official, they are not considered reliable for some very good reasons, which are;

                                    1. The extraction is incomplete. (Efficacy)
                                    2. The water and heat involved promote hydrolysis.
                                    3. Prone to contamination by microorganism.

However, for information purposes the prior official methods are given. All the process operations described are carried out on single substances. The student is now in possession of sufficient information to understand the chemical and physical reasons why this is so. If the student attempts to combine the products of the extractions, they will see the chemical and physical reactions that occur. If the student uses glycerine or acetic acid as a part, or whole of a menstruum, they will observe a breakdown of the synergistic plant complex. We cannot play games with Nature around the test tubes.

To combine two or more crude drugs is to destroy the natural synergy of them all. The chemical groups of each plant, when reacting with each other, produce unpredictable results. We have no means of knowing the consequences, and neither can we in this case resort to Empiricism to explain away the anomalies. The evidence of this destruction is clearly visible when we combine two or more tinctures. The abomination that results from the use of acetic acid or glycerine is also plainly visible. 

The Infusions 10.18
The infusions (Infusa) are of two types. The first is the fresh (Recentium) infusion. Before dealing with the procedure there are some points that are common to all such preparations;

(A) Strength – 5%, i.e., 1:20 = 50 g per litre. (D) Length of infusion – 15-30 minutes, depending on substance.

(B) Solvent – Hot or cold distilled water. (E) Length of storage – Maximum 12 hours.

(C) Degree of comminution – 18 or 25 mesh.

Under no circumstances should infusions of potent drugs i.e. those that are subject to international protocols, be made for the purpose of therapy. In choosing a hot or cold process, remember that some drug constituents are damaged by heat and balance this with the fact that solubility will increase with temperature. A woody substance will require a lengthier infusion than that allowed for a leafy substance.

The infusion should be prepared in a heat resistant glass, porcelain or stainless steel vessel. It should have a close-fitting lid to prevent the escape of volatile principles such as essential oils. For convenience and ease of handling, enclose the comminutated drug in a muslin bag. Other materials of a closer weave tend to absorb the essential oils. The bag should be of such size to accommodate the expansion of the drug. Bags must be kept scrupulously clean to avoid problems of cross contamination. Proceed as follows;

1. Scald the vessel with boiling water; rinse and quarter fill the vessel with boiling water and allow to stand for 2 or 3 minutes or until the vessel is thoroughly warmed through.

2. Empty the vessel then add the comminutated drug and pour on the requisite amount of boiling water. Cover the vessel tightly and allow to infuse for an appropriate time. Agitate the vessel 2 or 3 times during the infusion process.

3. On termination of infusion, remove the drug and lightly express the liquid it contains. Pour the liquid into a clean graduated container and adjust to the requisite volume with distilled water.

The preparation should be kept covered and used within 12 hours. If smaller or larger quantities than 1 litre are required then any adjustments should be made on the basis that the preparation conforms to a 1:20 strength.

The Concentrated Infusions 10.19
The second type of infusion is the ‘Concentrated Infusion’. These preparations were first introduced into the British Pharmacopoeia in 1898 under the head of ‘Liquors’. That designation was withdrawn in the 1914 B.P. and they were renamed as ‘Concentrated Infusions’.

The major use was as ‘stock’ item, from which a pharmacist could prepare the standard infusion by dilution with distilled water. The ratio of drug to water was 1 : 2.5. As a preparation they stand as an archaic monument to pharmaceutical ingenuity, that involved double and triple maceration to avoid excessive amounts of menstruum that would need to be evaporated to achieve the required concentration.

The heat required would damage the preparation and would also result in the loss of volatile principles during the evaporation process. After concentration the preparation was adjusted to volume at 25% alcohol to preserve it from deterioration. The practicalities involved in the preparations were problematical, briefly the problems are summarized as follows;

(A) Water alone promoted hydrolysis and could only achieve partial extraction of the plant constituents, i.e., it is not possible to exhaust the drug.

(B) For drug plants that contained essential oils the solutions were supersaturated i.e., the oils could not be held in suspension.

(C) The degree of expansion of the dried crude drug in the majority of cases meant that the drug/menstruum ratio was insufficient to achieve even a partial extraction.

(D) The evaporation of water requires prolonged high heat therefore it was not possible to achieve concentration to standard without unacceptable damage to the drug constituents, therefore extraction by percolation was not an option.

All of this placed the practicing pharmacist in a quandary, i.e., they had to serve two masters; on one hand there was ‘Authority’ in the form of a ‘Legal’ standard as represented by the ‘Pharmacopoeia’ and on the other the ‘Physician’ whose practice can rarely keep abreast of research; whose prescription was also a ‘legal’ order, and who long continued to prescribe infusions contrary to the advance of knowledge.

A compromise was reached by which the extraction was achieved by dilute alcohol at a strength of 25%. Even this was not really a satisfactory answer because invariably the dilution with water required to produce a standard infusion produced precipitation and/or turbidity due to the change in menstruum strength. So not surprisingly such preparations were slowly displaced as ‘official’ standards were changed i.e., tacit acknowledgment that such preparations were lacking in efficacy. The prolonged boiling for the preparation of ‘Decoctions’ is contraindicated.

 

The British Herbal Pharmacopoeia, 10.20
The British Herbal Medicine Association in their quasi official publication the British Herbal Pharmacopoeia has reintroduced the concentrated infusions under the term ‘liquid extractions’.

The preparations conform to the ‘official’ designation in that the drug/menstruum ratio is 1:1, i.e., 1 g is equivalent to 1ml. However the menstruum lacks the solvent power of that of a true extract and in that respect are inferior to the official ‘tinctures’. This may be seen in the following short Table representing a small sampling from the 233 monographs contained in the BHP 1983.

Table 10.20A

It was formerly a ‘convention’ of orthodox pharmacy that in preparing a crude drug that was not ‘official’, i.e. one for which there was no monograph in the pharmacopoeia then a concentrated infusion was ‘sine qua non’ which is from the Latin, meaning, “without which, not”. Obviously the scientific committee who worked on behalf of the BHMA have chosen to continue that convention in spite of the fact that there is now a wealth of information available for most of the crude drugs listed in the BHP.

Choosing an Appropriate Extraction Process 10.21
When considering a crude drug for extraction purposes thought must be given to whether the drug is classified as ‘organized’ or ‘unorganized’. If the drug has no clearly defined cellular construction it is unorganized. The maceration process is the only method suitable for unorganized drugs such as gums, resins, oleo-resins etc. Such materials are unsuitable for percolation because the residues would block the percolation process. The same restriction will also apply to crude organized drugs that produce large amounts of mucilage e.g. flax or Psyllium seed.

In other cases if a drug for whatever reason cannot be reduced to a powder then it is not suitable for a percolation process. Some drug materials e.g. Garlic and Squill are extremely hygroscopic and in the presence of water tend to fuse into lumps which make them unsuitable for the percolation process.

Extraction by Maceration 10.22
In a chemical sense the term ‘maceration’ means to ‘soften and separate the constituent parts of a substance in a liquid’.

The alchemical or hermetic term for the process was ‘digestion’ and it differed from the orthodox process in that the digestion was carried out at a constant low heat. i.e. a temperature not below 25°C or exceeding 35°C.

The Spagyrist had no thermometer, and judging the fire too fierce, would embed the digesting flask and its contents in horse dung. To ensure a constant and even gentle heat which is produced by fermentation of the manure.

We of course may also use a thermostat. At night fall the Spagyrist would remove the flask from the dung and allow it to cool in the night air. At sunrise the flask would be replaced in the dung. We simply turn off the  heat.

The process of digestion was continued for either a lunar month of 28 days (4 x 7) or a philosophical month of 40 days. The precise period was judged according to the work to be accomplished.

It is usual for the orthodox preparations to be macerated for a period of 7 days; in the language of alchemy this was a 7 fold circulation. The maceration is carried out at room temperature.

Tinctures by Maceration 10.23
Prior to the introduction of the technique of percolation, maceration was the universal method of producing strong extracts of crude drugs.

The results varied widely until reliable methods of assay allowed such tinctures to be chemically adjusted to the known level of a single ‘active’ constituent.

The following is a description of maceration, which is the general process given in the various issues of the British Pharmacopoeia.

Place the solid materials with the whole of the
menstruum in a closed vessel and allow to stand
for 7 days, shaking occasionally . Strain, press
the marc, and mix the liquids obtained. Clarify by subsidence or filtration.

The general method employed in the United States of America corresponded to the following description;

Macerate the drug in 75% of the menstruum, agitating regularly over a period of 3 days or until the extraction is complete. Transfer the mixture to a filter. When the liquid has drained wash the filter with the reserved portion of the menstruum, press the marc and adjust the filtrate to 1000 ml and mix thoroughly.

When comparing both methods it will be seen that the British process omitted to adjust the tincture for volume. This was not an oversight on the part of the BP and the process took account of the different methods employed to ‘press the marc’ so that uniformity of strength in the finished product was maintained. For example;

Table 10.23A

With the proviso that the volume is not adjusted to 1000 ml, then uniformity of dose is maintained. Whereas using the American method, whereby the preparation is adjusted in each case to 1000 ml, then the percentage weight in volume of the drug for each method of expression will alter thus uniformity does not exist for dosage purposes.

It must understood that this is no small matter in terms of potent drugs. Such variations could have tragic consequences. The therapeutic index of a drug may show a very small margin between effective (ED) dose and lethal (LD) dose.

For the Homeopath such variations are greatly magnified, and make a nonsense of diagnostic posology and the potentising process. It may be seen from the British process that even by use of a hydraulic press that the marc still contains a proportion of the menstruum and the soluble constituents, the proportion of which decreases as the efficiency of the expression process increases.

Unless one has use of a hydraulic press, the product from an organized drug manufactured by the maceration process, at its very best will be variable for Galenic Tinctures. If circumstances dictate that a tincture of an organized drug be made by maceration, use the British method and do not adjust the volume.

Tinctures from Unorganised Drugs 10.24
Maceration is the only feasible method of producing a tincture from an unorganized drug such as gum benzoin or propolis resin.

The marc from the exudates is usually slimy or gummy and may also consist of various types of debris, e.g., insect parts, fragments of soil or plant parts. The gums are insoluble in alcohol while the resins or oleo-resins will pass completely into solution. The gum and debris will sink to the bottom of the maceration vessel.

The separation of the supernatant liquid is usually by simple decantation or if required by filtration. There is no advantage to be gained by attempting to press the marc because all of the soluble constituents have entered into solution. Unlike the organized drug the solution is adjusted to volume.

Summary of Maceration Processes 10.25
(A) The Organized Drug. The marc of an organized drug will hold around 1.5 times its dry weight of menstruum, e.g., 500g of dry crude drug when saturated with menstruum would weigh circa 2 kg. That is the equivalent of a drug/menstruum ratio of 1:3. Obviously there is insufficient menstruum to extract the drug by maceration. Therefore, a standard tincture is 1:4.

1. Comminute the crude drug as appropriate and place it in a wide neck jar or flask. Pour in the total menstruum and seal the flask. Leave to macerate in a warm dark place.

2. Shake the maceration 2 or 3 times daily for 7 days.

3. After the 7 days, separate the menstruum from the marc by filtration. Press the marc and add the expressed liquid to the separated portion. Seal the flask, shake and leave to settle for 24 hours.

4. Clarify the tincture by a single filtration. Seal the flask and store in a cool place until required. Do not adjust the volume.

Maceration and storage should be carried out in a dark place, as a matter of routine. This because of the deleterious effect of light on the extracted substances, i.e., a catabolic breakdown occurs. Never over filter a tincture or extract lest it is altered or weakened. If after the 1^st filtration the liquid is not clear and bright then set the flask aside and allow to clear by subsidence. When required for use take care not to disturb any sediment and remove the liquid by siphon or large syringe.

There have been moves to standardize tinctures by international protocol at a strength of 1:5. This avoids occasional problems of too little menstruum for a satisfactory extraction due to enhanced absorption by some materials. However, many countries follow their own protocols in this respect.

(B) The Unorganized Drug. The major differences in procedures for unorganized drugs are as follows;

1. Crush the material and macerate the substance in 80% of the menstruum specified.

2. Shake the maceration 2 or 3 times daily for 3 days or until solution is complete.

3. Separate the marc from the extraction by filtration. Wash the marc across the filter with the reserved 20% of menstruum. Do not press the marc.

4. Finally adjust the tincture to the required volume by the addition of further menstruum. Uniformity is achieved because extraction of the unorganized substance is almost total.

Concentrated Preparations 10.26
All extracts below 1:4 are concentrated preparations. At one time such products were prepared by double and triple maceration techniques that are now abandoned, being lengthy in procedure and relatively inefficient when compared with the percolation process that replaced them.

Drug and Menstruum Ratios 10.27
The most common proportions of drug to menstruum are as follows;

Table 10.27A

It is most important that drug/menstruum ratios are accurately adhered to and all containers from which the preparation is dispensed should be clearly marked with the ratio, e.g., Tr Lobelia 1:8. Remember that the ratio will determine the therapeutic dose of the substance.

Module continues as 10B

Library
Pharmageddon Herbal Block Index

 

Earth Air Fire and Water
The Pharmageddon Herbal
Chapter 6

The Essential Distillation

Introduction.
The distiller’s pot goes back to the cradles of civilisation. Modern Scholars have expressed puzzlement about the obvious antiquity of the methods and means, yet there was little mention of alcohol until the leakage of Arabic Science into Europe during the 12^th Century AD. Perhaps it was because the substance was considered sacred. The Essentia, the Mercury, the soul of the plant.

Distillation is a means of obtaining a chemically pure substance. A means of separating the wanted from the unwanted.

We may be sure that those ancients probed the mysteries of all substances known to them. Wine would have been no exception.

The distillation apparatus is an ingenious method of emulating the planetary respiration and precipitation cycle. Symbolically it is the manipulation of Earth Air Fire and Water.

In the mundane sense it is an indispensable tool. Which by the use of measurement we may produce phenomena on demand, but within limits. This is the work of a technician and not of a master.The Herbologist makes use of 4 major processes, they are;

1. Fermentation – Chemical action by yeasts.

2. Sublimation – Distillation of a solid, e.g. Stockholm Tar or Benzoin.

3. Calcination – Recovery of salts from extracted residues.

4. Distillation – Separation and purification

The principles and techniques involved in the operations remain unaltered by scale; If you are not familiar with laboratory equipment and safety procedures, then you are advised to obtain an appropriate manual from your local library. Alternatively laboratory safety manuals are available for down load from the internet.

Measurements 6.1
Success or failure, safe or toxic, effective or useless, are all determined by measurement, accurate or otherwise. The measurements involved are, volume for liquids, weight for solids and temperature for heat, kPa for pressure.

Domestic measuring devices are prone to gross error. For calibration purposes having a piece of equipment of known accuracy to which other items may be referred is essential.

Due to multiple factors, even the most sensitive of devices will have an area of uncertainty, e.g., the expansion and contraction of volumetric devices due to temperature. Manufacturers of laboratory equipment will state what the area of uncertainty is, and heat is involved, and at what temperature the tolerance holds good. If weight is involved, at what barometric pressure. The temperature is usually 20°C and barometric pressure of 101 kPa or 760mm Hg.

Average Uncertainty Factors. Table 6.1A

Instrument	Uncertainty
Thermometer Mercury in Glass – 10 to 110°C	± 0.2°C
Platform Balance – Weight of Solids	± 0.50 g
Triple Beam Balance	± 0.01 g
Graduated Cylinder – Liquid – 100 ml	± 0.20ml
Graduated Cylinder 50 ml	± 0.20 ml
Graduated Cylinder 25 ml	± 0.10 ml
Pipette (liquid) 25 ml	± 0.02 ml
Pipette 10 ml	± 0.01 ml

Glassware 6.2
Standard laboratory glassware is available in two grades, borosilicate or soda glass. Borosilicate is the better quality, and has greater resistance to thermal shock, which is caused by rapid expansion or contraction, on heating or cooling. If domestic items are used, ensure that they are heat resistant. Apparatus for specific tasks may be constructed by using glass tube and cork, or rubber stoppers. If that method is adopted, then a gas burner will be needed for the heating and bending of the glass tube, plus a set of cork borers.

The other option which is to be preferred, is to purchase glassware in sets with ground glass connections. Although the initial cost is higher, over a period of time it will prove to be the best economic option. Contamination problems associated with the cork and rubber stoppers are eliminated. Cleaning is facilitated and the apparatus is quickly and easily assembled or dismantled.

Suppliers will provide a catalogue on request. Ground glass necks and joints are available in a number of sizes. Ensure that all parts match. Each size has a code number, the first part of which designates the diameter of the large end in millimeters, and the second gives the length of the joint. Table 6.2A is representative of the most popular sizes and should be available ex-stock.

Standard Joints. Table 6.2A

American	British	Size Code
10/18	10/19	0
14/20	14/23	1
19/22	19/26	2
24/25	24/29	3
29/26	29/32	4
34/28	34/35	5
40/35	40/38	6
45/50	45/40	7
50/50	50/42	8
55/50	55/44	9

Figure 6.2A Ground Glass Joints.

 

 

Ground glass joints must be kept scrupulously clean. If working with heat it is advisable to very lightly grease the joints with laboratory grade grease which has been specially formulated for that purpose.

Construction points for small scale plant. 6.3
When considering the economics of small scale processing plant, there are four factors that need   to be balanced.

1. Construction Cost – The costs may be reduced by utilizing used dairy or food processing equipment. The main cost is for welding services.

2. Operational Cost – Energy use is a prime cost. Unwanted heat loss will add considerably to energy use, as will bad design. Faulty design produces increased labor costs, e.g., difficult load/unload procedures.

3. Maintenance – Parts and fittings that are awkward and difficult to clean will add considerably to labor costs.

4. Durability – Fragile parts such as sight glasses should have adequate protection. Seals and breakable joints that have to be dismantled should be of good quality. Stopcocks, taps and valves should be corrosion proof.

Contamination problems may easily arise because of the nature of the substances involved in the processing from chemical action of one substance on another. E.g., heavy metals leached from the equipment are in themselves toxic contaminants, which may then trigger a further reaction in the substance being operated on.

Great care should be taken in the selection of materials that will be in contact with solvents or herb extracts. If using plastics or rubbers, then ask the supplier for the specifications of use. Do not use glaze ware unless you know what type of glaze it is. There are also several physical factors that need to be considered, e.g.,

A. Strength and Weight – Will the equipment be fixed or portable? Will the equipment be able to withstand any stresses placed upon it?

B. It’s Durability – Parts that are in contact with liquids and vapors must be resistant to corrosion. Metals that are prone to rust should as far as possible be avoided

C. Thermal Expansion and Conductivity – When mating materials, which are different, remember that they will have differing thermal expansion rates. That will produce stress or fatigue with an increased risk of fracture. Distillation equipment and condensers should possess good thermal conductivity.

D. Cleansing and Sterilizing – Smooth polished surfaces will simplify cleaning and sterilizing and help in the prevention of the formation of heat resistant films.

Two of the most commonly used materials for plant construction are copper and stainless steel. If considering copper, then it is most important that all linings in contact with the herbal materials, liquids or vapors, must be tin plated. Copper is a heavy metal that can cause liver damage, a known hepatoxic. Stainless steel will meet all criteria. Costs may be kept to a minimum by purchasing and modifying used vats, fittings and tubing.

The Heavy Metals 6.4
The root cause of many of the degenerative diseases to which we are prone, may be found in the realm of the heavy metals. In the normal course of events nature deals with them by using naturally occurring Chelating agents, e.g., chlorophyll, hemoglobin and citric, lactic, malic and tartaric acids. The word ‘chelate’ is taken from the Greek and means claw. The claw takes hold of the offending atom of metal and aids its excretion from the body. Without a chelating agent the heavy metal accumulates in the liver and other organs in toxic amounts with predictable results.

Food and herbs grown using chemo-culture methods contains dangerous levels of heavy metals. Heavy metal contamination also occurs from contamination by processing equipment and storage containers; therefore caution is social responsibility which one may not neglect. The Monitoring and Assessment Research Center (MARC) Chelsea College. London, defines heavy metals as having an atomic weight higher than sodium and a specific gravity of more than 5.0 or over. That description fits more than 70 elements.

The American Environmental Protection Agency (EPA.) States that the most widespread of the heavy metals are as follows;

Arsenic	Cadmium	Chromium	Copper
Lead	Mercury	Nickel	Zinc

 

 

The Metals are listed alphabetically and not in order of quantity as found in the environment.

Distillation 6.5
The process of distillation involves a reversible change of state i.e. Liquid —> Vapour  —> Liquid.

A liquid is subjected to heat input to produce a vapour. The vapour is rapidly cooled to produce a liquid. Standard laboratory equipment is called a distillation train.

Simple Distillation Train Figure 6.5A

On the left is the boiling flask in which a liquid is steadily turned to vapour. Central is the water cooled condenser to change the vapour back to a liquid. On the right is the collecting vessel. Figure 6.5A represents the process in its basic form; to which one may add a thermometer to monitor the temperature of the liquid in the boiling flask. A heat source is needed to produce a sufficient volume of vapor from a liquid, and a cooling surface (condenser), to convert the vapor back to a liquid.

The Heat Source 6.6
If the liquid or vapor that is being operated on is explosive or inflammable then special precautions must be taken. If the liquid or vapor cannot be isolated, then an open flame as heat source should be avoided. For small scale operations using an electric hot plate or heating jacket is better, rather than a naked flame. If a naked flame is used with glassware, then placing a square of metal gauze or asbestos between the flame and the glass is advisable. This distributes the heat and guards against thermal shock. Better still, the boiling flask should stand in a water bath when distilling alcohol.

Temperature Regulation 6.7
Electric heating devices usually incorporate a thermostat to regulate temperature with precision. Temperature regulation is necessary to prevent decomposition of the product toward the end of a distillation process, or to avoid damage to heat sensitive natural products. Without a thermostat or thermometer an adequate control of temperature may be gained by using water, sand or oil baths.

The water bath is also commonly known as the bain-marie and is extremely useful. It will give a fixed maximum temperature of 95°C, thereby preventing the charring of products contained within a flask. The water bath is also used extensively for the evaporation or concentration of liquids.

A Simple Water Bath. Figure 6.7A

 

Evaporating Water Bath 6.7B

From the points covered by dehydration, it will be understood that all temperatures exceeding 60°C, herbal constituents are thermolabile and prone to damage. By substituting sand for water a fixed temperature of 105E C may be obtained. Substances such as glycerine and oil will produce temperatures between 150 and 300E C. However the Herbologist has no need to work at such temperatures, unless higher are needed for calcinations. Suffice to say that substances that decompose and release toxic vapours should be avoided. The points made in paragraph 6.6 should be noted.

The Condenser 6.8
An inadequate or inappropriate condenser is the prime cause of failure in self built distillation equipment. The task of the condenser is to rapidly lower the temperature of hot vapor to, or below its dew point temperature, to precipitate a liquid.There are many types of condensers, however, they all employ either air or a liquid as the means of removing heat from a hot vapor. The water-cooled condenser meets all the requirements.

When in use a condenser should be mounted in an oblique or vertical position to facilitate the drainage of the condensed vapors. The most common form of condenser is the tube within a tube, which on a laboratory scale is represented by the Liebig condenser as shown in Figure 6.5A. Alternatively, for greater efficiency in larger scale operations, the condenser may be multi tube. If the amount of cooling water available is a consideration then a coil within a tank will meet the requirements. The coil within the tank is usually referred to as a ‘worm’.

Figure 6.8A. The Multi tube and Coil type Condensers.

If using a condenser of the coil in the tank type, it will be found that the upper layer of water will heat up quite rapidly; this will effect the efficiency of the condenser, and it should be removed via the overflow pipe, by introducing fresh cooling water to the tank.

The heat energy may be partially recovered by feeding the warm overflow water back to the body of the still. If the still is operating continuously, then considerable economy of energy may be achieved by having a continuous regulated flow of cooling water to the tank. See Figure 6.19A. To calculate the rate of flow, proceed as follows;

ExampleCooling water into the tank = 10 C
Temperature of the distillate = 40 C
Temperature of the steam = 100 C

Obviously the temperature of the distillate may vary considerably; however, in this example the temperature difference between the steam and the distillate is 60°C. The following values are taken from Figure 4.38A.

1 kg of steam, on condensing, will release 2260 kJ of heat plus 4.2 kJ/kg/°C, i.e., 60 x 4.2 = 252 kJ, giving a total heat surrender of 2512 kJ/kg.

For reasons that will be explained later, the water that is fed back to the still should ideally be at a temperature of 90°C. Therefore, if the cooling water temperature is 10°C, we have 90°C – 10°C = 80°C.

To raise the temperature of the cooling water it will need 4.2 kJ/kg/°C, i.e., 336 kJ/kg. Theoretically, 1 kg of condensed steam will heat,

Steam/kJ/kg 2512 ÷ 336 = 7.4kg of feed water.

for each kg of distillate produced. If the still output is 10 kg (litre) per hour, then 74 litres of cooling water must be added in one hour, or 810 ml per minute. In practice, due to unavoidable losses, this figure may be reduced by 20%. To achieve the correct flow, simply adjust the cooling water tap until the still feed water is around 90°C. The temperature should be taken at regular intervals, and cooling water adjusted accordingly.

Condenser Efficiency 6.9
The heat transfer rate of a condenser must exceed the enthalpy of vaporization produced by the still, i.e., it must be capable of condensing the vapor produced. The amount of vapor generated is dependent on heat input per unit of time. Therefore, if purchasing a commercial unit, they will be designed to produce a given amount of distillate, in a given amount of time, e.g., 10 litres per hour. A condenser for such a still would need to cope with approximately 25,000 kJ/hr to convert all the vapor output from the still. For practical reasons, the condenser capacity must exceed the theoretical heat load by some 20%. The efficiency of the condenser will depend on the following factors;

A. The area of its cooling surface.

B. Its thermal conductivity. The actual rate of heat transfer for a tube(s) within a tube condenser will also depend on the velocity of the cooling water across the condenser tube(s).

C. The extent of the vapor/cooling surface contact, which will depend on the diameter of the vapor tube and the velocity of the vapor.

D. The temperature difference between the vapor and the cooling water. These factors taken as a body, determine the capacity of the condenser.

Condenser Capacity 6.10
Steam produced within a still at atmospheric pressure is said to be saturated, and can be seen as a mist or fog, which is comprised, vapor and very finely divided water particles. If it loses heat without a corresponding drop in pressure, the steam will promptly condense to water. The following extract from the steam Tables will help in making necessary calculations for the altitude at which a still may be operated. Round the figures to the nearest whole number.

Steam Data. Table 6.10A

Absolute Pressure (kPa)	Saturation Temperature (°C)	Sensible Heat (kJ/kg)	Enthalpy Latent Heat (kJ/kg)	Total Heat kJ/kg	Steam Volume (m³/kg)
95.00	98.20	411.43	2261.80	2673.20	1.777
100.00	99.63	417.46	2258.00	2675.00	1.694
101.30*	100.00	419.04	2257.00	2676.00	1.673
106.30	101.40	424.90	2253.30	2678.20	1.601

* Standard atmosphere. Sea level.

For example, let us assume that we have a single tube stainless steel condenser, and we want to know whether it will be suitable for a still, with an output of 10 litres of distilled water per hour.

Step 1. Calculate the area of the condensing tube. Example the tube is 0.750m long and a diameter of 1 cm

Area = Circumference of the tube x length

D x L = 3.14 x 1 x 750 = 2355cm = 0.235m²

Step 2. Consult Table 5.25A and determine the thermal conductivity, i.e., stainless steel 20 J/second/m² Remember that 1 watt = 1 Joule per second.

Step 3. Determine the difference between the saturated vapor temperature and that of the distillate. Assume distillate temperature as 40°C. therefore 100 – 40 = 60°C difference

Step 4. Calculate the thermal conductivity of the condenser tube, the thickness of the condenser tube wall is 1 mm.

Area x Conductivity x Temperature ÷ Wall thickness. 0.235 x 20 x 60 ÷ 0.01 = 28.20 kJ/second.

A still with a capacity of 10 litres/hr produces 1 litre every 6 minutes, or 1 kg of saturated steam every 6 minutes. Table 6 -10A shows that 1 kg of steam at atmospheric pressure, holds 2676 kJ of heat energy. Therefore at 28.2 kJ/sec the condenser tube can disperse 10,152 kJ in 6 minutes.

Thermal Conductivity of a Spiral Coil 6.11
Step 1. Determine the length of the tube in the coil by measuring the outer and inner diameter of 1 coil, add them and divide by 2, this will give the average diameter.

Step 2. Multiply the average diameter by the p (3.14), this will average circumference.

Step 3. Multiply the circumference by the number of coils, which gives an approximate length of the tube in the spiral.

Step 4. Proceed as in section 6 -10.

N.B. Due to simplification, the calculation method is not strictly accurate. However the margin of error is very small and will meet our purpose.

Distillation Techniques and Products 6.12
Distillation is important to the Herbologist in three main areas; Concentration – Purification – Separation. To achieve those ends four techniques are employed;

1. Simple distillation which is as Paragraph 6.5.

2. Fractional distillation of a substance, where components of different boiling points are separated.

3. Distillation under reduced pressure to avoid damage or chemical change to a substance, where a change in physical form is required.

4. Distillation in steam. This is the method most often used for the production of volatile oils.

There is one further technique, which is destructive distillation or pyrolysis, which will be covered under the heading of sublimation. For the Herbologist the two major products of distillation are the solvents, i.e., purified water and ethanol, without which, the science would be no more than a primitive art. From the techniques a diverse range of products and by products are obtained. For example;

Purified or distilled water – Aromatic waters – Ethanol – Essences/Spirits

Volatile oils – Extracts – Tinctures – Benzoic acid.

Boiling Points 6.13
Boiling, or ebullition, is the process that constitutes the difference between evaporation and distillation. When the vapor pressure of a liquid exceeds the pressure upon it, the liquid will commence to boil, (see Figure 4.44A). The boiling point of a pure substance is clearly defined and will boil at a given temperature for a given pressure. Therefore, a fluctuation in pressure will alter the boiling point. Consequently if using boiling points for identifying a substance, then pressure is a prime concern.

The organic compounds are organized into families, which have a similar shaped molecule and are called ‘homologous series’. For example the alcohol family comprises more than 70 members. Generally, the boiling points of a series will rise in line with an increase in molecular weight. Water does not belong to a homologous series.

Representative Alcohols. Table 6.13A

Alcohol	Molecular weight	Boiling point
Methanol	32.0	64.65°C
Ethanol	46.1	78.52°C
Amyl (fusel)	88.1	138.25°C
Glycerol	92.1	290.0°C

Ethanol as a pure substance cannot be separated completely from water by the distillation process. This is because, when ethanol is at a concentration of 95.5% it forms a constant boiling mixture with the 4.5% water, which will distill over with it. The subject of ethanol will be covered in greater detail in the module that deal with solvents used and their preparation.

Vapour Composition Table 6.12B

Temperature °C	% Ethanol	% Water
78.5	86	14
80.0	83	17
82.0	79	21
84.0	76	24
86.0	72	28
88.0	67	33
90.0	62	38

 

Chapter 6 Part 2

 

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