A: Infrared Absorption 197K.

B: The 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.

Standard stock solution— Dissolve an accurately weighed quantity of USP Temazepam RS in chloroform, and dilute quantitatively and stepwise with chloroform to obtain a solution having a known concentration of about 10 mg per mL.

Standard solutions A and B— Dilute accurately measured volumes of Standard stock solution quantitatively with chloroform to obtain Standard solutions A and B having known concentrations of about 0.1 and 0.05 mg per mL, respectively.

Test solution— Transfer about 100 mg of Temazepam, accurately weighed, to a 10-mL volumetric flask, add chloroform to volume, and mix.

Procedure— Separately apply 10 µL of the Test solution and 10 µL of each Standard solution to a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Position the plate in a chromatographic chamber, and develop the chromatograms in a solvent system consisting of cyclohexane, chloroform, methanol, and ammonium hydroxide (50:40:12:1) until the solvent front has moved about 10 cm above the point of application. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Examine the plate under short-wavelength UV light, and compare the intensities of any secondary spots observed in the chromatogram of the Test solution with those of the principal spots in the chromatograms of the Standard solutions: no secondary spot obtained from the Test solution is greater in intensity than 1.0%, and the sum of the intensities of secondary spots obtained from the Test solution corresponds to not more than 2.0%.

Buffer solution— Dissolve 5.444 g of monobasic potassium phosphate in 2000 mL of water. Adjust with phosphoric acid to a pH of 3.0.

Mobile phase— Prepare a filtered and degassed mixture of Buffer solution and acetonitrile (53:47). Make adjustments if necessary (see System Suitability under Chromatography 621).

Internal standard solution— Dissolve an accurately weighed quantity of benzophenone in a mixture of methanol and water (9:1), and dilute quantitatively and stepwise with the same solvent to obtain a solution having a concentration of 0.2 mg per mL.

Standard preparation— Dissolve an accurately weighed quantity of USP Temazepam RS in Internal standard solution to obtain a solution having a known concentration of 0.2 mg per mL.

Assay preparation— Transfer about 40.0 mg of temazepam, accurately weighed, to a 200-mL volumetric flask, add about 150 mL of Internal standard solution, mix, and dilute with Internal standard solution to volume.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 25-cm column that contains packing L16. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 800 theoretical plates; the tailing factor is not more than 2; the resolution, R, between the temazepam peak and any other peak is not less than 1, and the relative standard deviation for replicate injections is not more than 2.0%.

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. The relative retention times are about 1.0 for temazepam and 2.0 for benzophenone. Calculate the quantity, in mg, of C16H13ClN2O2 in the portion of Temazepam taken by the formula: in which C is the concentration, in mg per mL, of USP Temazepam RS in the Standard preparation; and RU and RS are the peak response ratios obtained from the Assay preparation and the Standard preparation, respectively.