(Ph Eur monograph 1772)
C42H65NO16 840 53956-04-0
Mixture of ammonium 18a- and 18b-glycyrrhizate (ammonium (20b)-3b-[(2-O-b-d-glucopyranuronosyl-a-d-glucopyranuronosyl)oxy]-11-oxoolean-12-en-29-oate), the 18b-isomer being the main component.
98.0 per cent to 102.0 per cent (anhydrous substance).
White to yellowish-white powder.
Slightly soluble in water, very slightly soluble in ethanol, practically insoluble in acetone. It dissolves in dilute solutions of acids and of alkali hydroxides.
A. Infrared absorption spectrophotometry (2.2.24).
Ammonium glycyrrhizate CRS.
B. Dissolve 0.1 g in 20 ml of water R, add 2 ml of dilute sodium hydroxide solution R and heat cautiously. On heating, the solution gives off vapours that may be identified by the alkaline reaction of wet litmus paper (2.3.1).
Dissolve 1.0 g in a 20 per cent V/V solution of alcohol R and dilute to 100.0 ml with the same solution.
Appearance of solution
Solution S is clear (2.2.1) and not more intensely coloured than reference solution BY7 (2.2.2, Method I).
Specific optical rotation (2.2.7)
+ 49.0 to + 54.0 (anhydrous substance).
Dissolve 0.5 g in a 50 per cent V/V solution of alcohol R and dilute to 50.0 ml with the same solution.
Liquid chromatography (2.2.29).
Dissolve 0.100 g of the substance to be examined in the mobile phase and dilute to 100.0 ml with the mobile phase.
Reference solution (a)
Dilute 1.0 ml of the test solution to 20.0 ml with the mobile phase.
Reference solution (b)
Dissolve 50 mg of ammonium glycyrrhizate CRS in the mobile phase and dilute to 50.0 ml with the mobile phase. Dilute 1.0 ml of the solution to 20.0 ml with the mobile phase.
size: l = 0.25 m, Ø = 4.0 mm,
stationary phase: octadecylsilyl silica gel for chromatography R (5–10 µm).
Glacial acetic acid R, acetonitrile R, water R (6:380:614 V/V/V).
Flow rate 1.2 ml/min.
Detection Spectrophotometer at 254 nm.
Injection 10 µl.
3 times the retention time of the principal peak due to 18b-glycyrrhizic acid.
With reference to 18b-glycyrrhizic acid (retention time = about 8 min): impurity A = about 0.8; 18a-glycyrrhizic acid = about 1.2.
Reference solution (b):
resolution: minimum of 2.0 between the principal peak due to 18b-glycyrrhizic acid and the peak due to 18a-glycyrrhizic acid.
18a-glycyrrhizic acid: not more than twice the sum of the areas of the peaks in the chromatogram obtained with reference solution (a) (10.0 per cent),
impurity A: not more than the sum of the areas of the peaks in the chromatogram obtained with reference solution (a) (5.0 per cent),
any other impurity: not more than 0.4 times the sum of the areas of the peaks in the chromatogram obtained with reference solution (a) (2.0 per cent),
total of other impurities: not more than 1.4 times the sum of the areas of the peaks in the chromatogram obtained with reference solution (a) (7.0 per cent),
disregard limit: 0.04 times the sum of the areas of the peaks in the chromatogram obtained with reference solution (a) (0.2 per cent).
Heavy metals (2.4.8)
Maximum 20 ppm.
1.0 g complies with limit test C. Prepare the standard using 2 ml of lead standard solution (10 ppm Pb) R.
Maximum 4.0 per cent, determined on 0.250 g.
Sulphated ash (2.4.14)
Maximum 0.2 per cent, determined on 1.0 g.
Dissolve 0.600 g in 60 ml of acetic acid R heating at 80 °C if necessary. Cool and carry out a potentiometric titration (2.2.20) using 0.1 M perchloric acid.
1 ml of 0.1 M perchloric acid is equivalent to 84.0 mg of C42H65NO16.
A. (4β,20β)-3β-[(2-O-β-d-glucopyranuronosyl-a-d-glucopyranuronosyl)oxy]-23-hydroxy-11-oxoolean-12-en-29-oic acid (24-hydroxyglycyrrhizic acid).
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