A: The contents of the Capsules meet the requirements under Identification—Organic Nitrogenous Bases 181.

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

Medium: water; 500 mL.

Apparatus 1: 100 rpm.

Time: 30 minutes.

Mobile phase and Chromatographic system—Prepare as directed in the Assay.

Procedure— Inject a measured volume (about 50 µL) of a filtered portion of the solution under test into the chromatograph, record the chromatogram, and measure the response for the major peak. Determine the quantity of C17H21NO·HCl dissolved in comparison with a Standard solution having a known concentration of USP Diphenhydramine Hydrochloride RS in the same medium and similarly chromatographed.

Tolerances— Not less than 80% (Q) of the labeled amount of C17H21NO·HCl is dissolved in 30 minutes.

(Official January 1, 2007)

Mobile phase, Standard preparation, System suitability solution, and Chromatographic system—Prepare as directed in the Assay under Diphenhydramine Hydrochloride.

Assay preparation— Weigh and combine the contents of not fewer than 20 Capsules. Transfer an accurately weighed portion of the combined Capsule contents, equivalent to about 50 mg of diphenhydramine hydrochloride, to a 100-mL volumetric flask. Dissolve in and dilute with water to volume, mix, and filter.

Procedure— Proceed as directed for Procedure in the Assay under Diphenhydramine Hydrochloride. Calculate the quantity, in mg, of C17H21NO·HCl in the portion of Capsule contents taken by the formula: in which C is the concentration, in mg per mL, of USP Diphenhydramine Hydrochloride RS in the Standard preparation, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.