Medium: dilute hydrochloric acid (1 in 100); 1000 mL.

Apparatus 1: 100 rpm.

Time: 30 minutes.

Procedure— Determine the amount of C16H21NO2·HCl dissolved from UV absorbances at the wavelength of maximum absorbance at about 289 nm of filtered portions of the solution under test, suitably diluted with Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Propranolol Hydrochloride RS in the same medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C16H21NO2·HCl is dissolved in 30 minutes.

Procedure for content uniformity— Transfer 1 Tablet to a 100-mL volumetric flask, add 5 mL of dilute hydrochloric acid (1 in 100), and let stand, swirling occasionally, until it is disintegrated. Add about 70 mL of methanol, and sonicate for about 1 minute. Dilute with methanol to volume, mix, and centrifuge a portion of the solution. Dilute an aliquot of the clear solution quantitatively with methanol to provide a solution containing about 40 µg of propranolol hydrochloride per mL. Concomitantly determine the absorbances of this solution and of a solution of USP Propranolol Hydrochloride RS in methanol, at a known concentration of about 40 µg per mL, in 1-cm cells at the wavelength of maximum absorbance at about 290 nm, with a suitable spectrophotometer, using methanol as the blank. Calculate the quantity, in mg, of C16H21NO2·HCl in the Tablet by the formula: in which T is the labeled quantity, in mg, of propranolol hydrochloride in the Tablet, D is the concentration, in µg per mL, of the solution from the Tablet, based on the labeled quantity per Tablet and the extent of dilution, C is the concentration, in µg per mL, of USP Propranolol Hydrochloride RS in the Standard solution, and AU and AS are the absorbances of the solution from the Tablet and the Standard solution, respectively.

Mobile phase, Standard preparation, Resolution solution, and Chromatographic system— Prepare as directed in the Assay under Propranolol Hydrochloride.

Assay preparation— Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 50 mg of propranolol hydrochloride, to a 50-mL volumetric flask, add 40 mL of methanol, shake, and sonicate for 5 minutes. Dilute with methanol to volume, mix, and filter through a 0.7-µm or finer porosity filter. Transfer 5.0 mL of this solution to a 25-mL volumetric flask, dilute with methanol to volume, and mix.

Procedure— Proceed as directed for Procedure in the Assay under Propranolol Hydrochloride. Calculate the quantity, in mg, of C16H21NO2·HCl in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Propranolol Hydrochloride in the Standard preparation, and rU and rS are the propranolol peak responses obtained from the Assay preparation and the Standard preparation, respectively.