Tragacanth B.P. 1958
Compiled and edited
by
Ivor
Hughes
Tragacanth Trag.
Tragacanth is the dried gummy exudation obtained by
incision from Astragalus gummifer Labill.
and some other species of Astragalus.
Description.
Thin flattened flakes, irregularly oblong or more or less curved, marked on
the surface by concentric ridges, frequently about 2.5 cm. long and 12 mm.
wide; white or pale yellowish-white, somewhat translucent; horny; fracture,
short. Odourless; almost tasteless.
Identification.
A. To 4 ml. of a 0.5 per cent w/v solution, add 0.5 ml. of
hydrochloric acid and heat for thirty minutes in a water-bath. Divide the
liquid into two parts. To one part add 1.5 ml. of sodium hydroxide solution
and 3 ml. of potassium cupri-tartrate solution, and warm in a water-bath; a
red precipitate is produced. To the remainder of the liquid, add barium
chloride solution; no precipitate is produced (distinction from agar).
B. To a 0.5 per cent w/v solution, add a 20 per cent w/v solution of lead acetate; a voluminous, flocculent precipitate is produced (distinction from acacia, from ghatti gum, and from sterculia).
C. Mount a small quantity, in powder, in ruthenium red solution, and examine microscopically; the particles do not acquire a pink colour (distinction from sterculia and from agar).
D. To 0.1 g., in powder, add 1 ml. of N/50 iodine; the mixture acquires an olive-green colour (distinction from acacia and from agar).
Apparent viscosity.
Grind a sample, without allowing it to become appreciably heated,
until the whole passes through a No. 30 sieve. Place
0.80 g., accurately weighed, in a dry 500-m1.
conical flask and add 5 ml. of alcohol (95 per cent). Ensure that the
gum is completely wetted and evenly dispersed over the inner surface of the
flask, add 195 ml. of water as quickly as possible, and shake. Allow to
stand for one hour, swirling frequently.
Attach a reflux condenser to the flask and immerse in vigorously boiling water so that the surface of the water is about 2.5 cm. above the surface of the mucilage. Continue heating for one hour, gently swirling at intervals of fifteen minutes without removing the flask from the water.
Remove the flask from the water, stopper, shake frequently during a period of two hours, and allow to stand for twenty-four hours. Determine the reflux time, at 20�, of 50 ml. using a Redwood No. I viscometer. Multiply the mean of six readings by 27/x, where x is the efflux time, at 20�, of 50 ml. of water determined in the same instrument. The corrected efflux time is not less than 100 seconds.
Solubility in water.
Sparingly soluble in water, but swells into
an homogeneous, adhesive, gelatinous mass.
Starch.
When treated with water and then with N/50 iodine, it is not
coloured but may show minute scattered blue points; when examined
microscopically, only a few groups of small, rounded starch grains are
visible.
Acid-insoluble ash.
Not more than 0-5 per cent.
Ash.
Not more than 4-0 per cent.
Foreign organic matter.
Not more than 1-0 per cent.
Storage.
Tragacanth should be kept in a well-closed container.
POWDERED TRAGACANTH
(Tragacanthae Pulvis)
Description.
White; in colourless, angular, microscopic fragments which, when
treated with water, increase in size, and finally disappear.
Identification;
Solubility In water; Starch; Acid-insoluble
ash; Ash; Storage. Complies with the requirements
for Identification, Solubility In water, Starch, Acid-insoluble ash, Ash,
and Storage stated under Tragacanth.
Apparent viscosity.
Carry out the test for Apparent
viscosity described under Tragacanth, omitting the grinding and using 0.88
g., accurately weighed. The corrected efflux time is not less than 100
seconds.
Preparations.
COMPOUND TRAGACANTH POWDER
Pulvis Tragacanthae Compositus Co. Trag.Pdr.
Pulv.Trag. Co.
Tragacanth, finely
powdered . . .
, 150 g.
Acacia, finely powdered .
. . .
. 200 g.
Starch, finely powdered .
. . .
. 200 g.
Sucrose, finely powdered. .
. . .
450 g. Mix.
TRAGACANTH MUCILAGE Trag. Mucil.
Tragacanth, finely powdered .
. , 12.5 g.
Alcohol (90 per cent) . .
. . 25 ml.
Chloroform Water, sufficient to produce .
1000 ml.
Mix the Tragacanth with the Alcohol (90 per cent) in a dry bottle, add, as quickly as possible, sufficient Chloroform Water to produce 1000 ml., and shake vigorously.
The image is from Denstons Pharmacognosy.
Related Monographs :
Acacia B.P.
also,
Acacia and other Gums Martindales 24th
