Procedure for content uniformity
Transfer 1 finely powdered Tablet to a 250-mL volumetric flask, add 50 mL of water and 3 mL of hydrochloric acid, mix, and allow to stand for 15 minutes with occasional agitation. Dilute with water to volume, mix, and filter, discarding the first 20 mL of the filtrate. Dilute a portion of the subsequent filtrate quantitatively and stepwise, if necessary, with water to provide a solution containing approximately 2.4 µg of papaverine hydrochloride per mL. Concomitantly determine the absorbances of this solution and a solution of
USP Papaverine Hydrochloride RS, in the same medium at a concentration of about 2.4 µg per mL, in 1-cm cells, at the wavelength of maximum absorbance at about 250 nm, with a suitable spectrophotometer, using water as the blank. Calculate the quantity, in mg, of C
20H
21NO
4·HCl in the Tablet by the formula:
(TC / D)(AU / AS),
in which
T is the labeled quantity, in mg, of papaverine hydrochloride in the Tablet;
C is the concentration, in µg per mL, of
USP Papaverine Hydrochloride RS in the Standard solution;
D is the concentration, in µg per mL, of the solution from the Tablet based upon the labeled quantity per Tablet and the extent of dilution; and
AU and
AS are the absorbances of the solution from the Tablet and the Standard solution, respectively.