A: Infrared Absorption 197K.

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

(Official January 1, 2007)

Buffer solution— Transfer 1.36 g of monobasic potassium phosphate to a 1000-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Adjust the solution with 10% sodium hydroxide (w/v) to a pH of 7.5, and filter.

Mobile phase— Prepare a filtered and degassed mixture of Buffer solution and acetonitrile (60:40). Make adjustments if necessary (see System Suitability under Chromatography 621).

Internal standard solution— Prepare a stock solution of propylparaben in methanol having a concentration of 2.5 mg per mL. Dilute 25.0 mL of the stock solution quantitatively with water to 500.0 mL, and mix.

Standard stock solution— Transfer about 50 mg of USP Buspirone Hydrochloride RS, accurately weighed, to a 100-mL volumetric flask, dissolve in 25 mL of 1 N hydrochloric acid, dilute with water to volume, and mix.

Standard preparation— Transfer 10.0 mL of the Standard stock solution to a 50-mL volumetric flask, add 10.0 mL of Internal standard solution, dilute with water to volume, and mix.

Assay preparation— Transfer about 50 mg of Buspirone Hydrochloride, accurately weighed, to a 100-mL volumetric flask, add 25 mL of 1 N hydrochloric acid, dilute with water to volume, and mix. Transfer 10.0 mL of this solution to a 50-mL volumetric flask, add 10.0 mL of the Internal standard solution, dilute with water to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the resolution, R, between buspirone hydrochloride and the internal standard is not less than 4; and the relative standard deviation determined from the buspirone peak response for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 25 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times of propylparaben and buspirone hydrochloride are about 0.55 and 1.0, respectively. Calculate the quantity, in mg, of C21H31N5O2·HCl in the portion of Buspirone Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of USP Buspirone Hydrochloride RS in the Standard preparation; and RU and RS are the peak response ratios of buspirone hydrochloride to propylparaben obtained from the Assay preparation and the Standard preparation, respectively.