Standard preparation— Prepare as directed in the Assay under Deslanoside.

Assay preparation— Transfer a volume of Injection, equivalent to about 600 µg of deslanoside, to a separator, and add 50 mL of water and 1 mL of 2 N sulfuric acid. Extract with four 30-mL portions of a mixture of 5 volumes of chloroform and 1 volume of n-propyl alcohol, washing each portion in a second separator containing 5 mL of water and filtering through cotton that previously has been moistened with chloroform. Combine the extracts, and evaporate on a steam bath, with the aid of a current of air, just to dryness. Transfer the residue, with the aid of a small volume of the chloroform–n-propyl alcohol mixture, to a 25-mL conical flask.

Procedure— Transfer 3.0 mL each of the Standard preparation and of alcohol to provide the blank to separate 25-mL conical flasks. Using these solutions and the Assay preparation, proceed as directed for Procedure in the Assay under Deslanoside, beginning with “Evaporate each with gentle warming.” Calculate the quantity, in µg, of C47H74O19 in each mL of the Injection taken by the formula: in which C is the concentration, in µg per mL, of USP Deslanoside RS in the Standard preparation; V is the volume, in mL, of Injection taken; and AU and AS are the maximum absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.