A: 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.

B: Transfer an accurately weighed amount of Capsule contents, equivalent to about 10 mg of diazepam, to a 50-mL centrifuge tube, and add 2 mL of acetone. Place the centrifuge tube in an ultrasonic bath for 5 minutes, and centrifuge. Using 100 µL of the supernatant as the test solution, and 100 µL of a solution of USP Diazepam RS in acetone containing 5 mg per mL as the Standard solution, proceed as directed for Identification test B under Diazepam.

Medium: 0.01 N hydrochloric acid; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C16H13ClN2O dissolved by employing UV absorption at the wavelength of maximum absorbance at about 284 nm on filtered portions of the solution under test, suitably diluted with Dissolution Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Diazepam RS in the same Medium.

Tolerances— Not less than 85% (Q) of the labeled amount of C16H13ClN2O is dissolved in 45 minutes.

(Official January 1, 2007)

Mobile phase, System suitability solution, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Diazepam.

Assay preparation— Weigh and mix the contents of not less than 20 Capsules. Transfer an accurately weighed portion of the capsule contents, equivalent to about 10 mg of diazepam, to a 100-mL volumetric flask. Add 50 mL of methanol, sonicate for 5 minutes, shake by mechanical means for 5 minutes, dilute with methanol to volume, mix, and filter, discarding the first few mL of the filtrate.

Procedure— Separately inject equal volumes (about 10 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 diazepam (C16H13ClN2O) in the portion of Capsules taken by the formula: in which C is the concentration, in mg per mL, of USP Diazepam RS in the Standard preparation, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.