THE DETERMINATION OF TOTAL ALKALOIDS IN CHINESE DRUG TSINGJIU

A method for determining the total alkaloids of the Chinese drug Tsingjiu (秦艽) (Gentiana macrophylla) based on titration with silicotungstic acid was found. Weigh out accurately 2 g of pulverized (80 mesh) sample. Macerate it in a glass-stoppered flask with 50 ml of a mixture of chloroform-methanol-concentrated ammonia water (75: 25: 5) for 48 hours with occasional shaking. Take exactly 25 ml of the filtrate, evaporate and dissolve the residue in 0.6 N acetic acid, Impurities in the acetic acid solution are removed with lead acetate and the excess of Pb⁺² is removed by sodium sulphate. The clear filtrate is adjusted to about 50 ml with an acidity at about 0.5 N. The solution is titrated with 0.01 M silicotungstic acid, using malachite green as an outside indicator. Results are calculated on gentianine (C₁0H₉O₂N).