- Borntrager’s test: To 0.1 g of calcium sennosides add 5 ml dilute HCl and boil on a water bath for 2 min. Filter, cool and shake the filtrate with 2 ml ether. Separate the organic layer, add a few drops of 10% ammonia and shake vigorously. A rose red colour is seen in the aqueous layer.
- Modified Borntrager’s test: To 0.1 g of the drug add 5ml ferric chloride and 5ml dilute hydrochloric acid. Heat for 5 min on a boiling water bath. Cool, shake with ether and add equal volume of ammonia. An intense red colour is formed in the ammoniacal layer confirming the presence of anthraquinone glycoside.
- Paper chromatography of the glycosides dissolved in alcohol is developed in the lower aqueous layer of a mixture of water, acetone and benzene (2:1:4), the chamber being equilibrated with the upper phase of the solvent mixture contained in a beaker in the chamber. It is developed by spraying with 0.5% magnesium acetate in methanol followed by heating to 100° for 3 to 5 min. Sennosides are seen as distinct orange spots.
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