A: Infrared Absorption 197M.

B: The retention time of the major peak for propranolol in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

C: It responds to the tests for Chloride 191.

Test solution: 40 mg per mL, in water.

Mobile phase— Dissolve 0.5 g of sodium dodecyl sulfate in 18 mL of 0.15 M phosphoric acid, add 90 mL of acetonitrile and 90 mL of methanol, dilute with water to make 250 mL, mix, and pass through a filter having a 0.5-µm or finer porosity. Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Quantitatively dissolve an accurately weighed quantity of USP Propranolol Hydrochloride RS in methanol to obtain a stock solution having a known concentration of about 1 mg per mL. Transfer 5.0 mL of this solution to a 25-mL volumetric flask, dilute with methanol to volume, mix, and pass through a filter having a 0.7-µm or finer porosity. This solution contains about 0.2 mg of USP Propranolol Hydrochloride RS per mL.

Resolution solution— Prepare a solution of procainamide hydrochloride in methanol containing about 0.25 mg per mL. Transfer 5 mL of this solution and 5 mL of the stock solution used to prepare the Standard preparation to a 25-mL volumetric flask, dilute with methanol to volume, and mix.

Assay preparation— Transfer about 50 mg of Propranolol Hydrochloride, accurately weighed, to a 50-mL volumetric flask, add 45 mL of methanol, shake, and sonicate for 5 minutes. Dilute with methanol to volume, mix, and pass through a filter having a 0.7-µm or finer porosity. Transfer 5.0 mL of this solution to a 25-mL volumetric flask, dilute with methanol to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 290-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L7. The flow rate is about 1.5 mL per minute. Chromatograph the Resolution solution, and record the peak responses as directed for Procedure: the relative retention times are about 0.6 for procainamide and 1.0 for propranolol; and the resolution, R, between the procainamide and the propranolol peaks is not less than 2.0. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor for the propranolol peak is not more than 3.0; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C16H21NO2·HCl in the portion of Propranolol Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of USP Propranolol Hydrochloride RS in the Standard preparation; and rU and rS are the propranolol peak responses obtained from the Assay preparation and the Standard preparation, respectively.