A: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,both relative to the internal standard as obtained in the Assay.

B: The RFvalue of the principal spot in the chromatogram of the Test solutionobtained in the test for Related compoundscorresponds to that in the chromatogram of Standard solution A.

Medium: 1%sodium lauryl sulfate;900mL.

Apparatus 2: 50rpm.

Time: 30minutes.

Procedure— Determine the amount of C17H11ClF4N2Sdissolved from UVabsorbances at the wavelength of maximum absorbance at about 287nm on filtered portions of the solution under test in comparison with a Standard solution having a known concentration of USP Quazepam RSdissolved in a small volume of methanol and diluted with Dissolution Medium.

Tolerances— Not less than 80%(Q)of the labeled amount of C17H11ClF4N2Sis dissolved in 30minutes.

Change to read:

Test solution— Grind 10Tablets to a fine powder.Dissolve an accurately weighed portion of the powder in methylene chloride to obtain a solution having a concentration of 10mg of quazepam per mL.Mix for 30minutes,and centrifuge.

Standard solution A— Dissolve an accurately weighed quantity of USP Quazepam RSin methylene chloride to obtain a solution having a known concentration of about 10mg per mL.

Standard solution B— Dissolve an accurately weighed quantity of USP Quazepam RSin methylene chloride to obtain a solution having a known concentration of about 0.04mg per mL(0.2%).

Standard solution C— Dissolve an accurately weighed quantity of USP Quazepam Related Compound A RSUSP28in methylene chloride to obtain a solution having a known concentration of about 0.3mg per mL(1.5%).

Procedure— Separately apply 10µLeach of the Test Solutionand Standard solution Aand 5µLeach of Standard solutions Band Cto a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Allow the spots to dry,and develop the chromatogram in a solvent system consisting of a mixture of cyclohexane,ethyl acetate,and ether (170:40:25)in a paper-lined tank until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,allow to air-dry,and examine the plate under short-wavelength UVlight.Compare the intensity of the secondary spot in the chromatogram of the Test solutionhaving the same RFvalue as the principal spot in the chromatogram of Standard solution C.The spot is not larger or more intense than the principal spot obtained from Standard solution C.Compare the intensities of any additional secondary spots observed in the chromatogram of the Test solutionwith that of the principal spot in the chromatogram of Standard solution B:no additional secondary spot from the chromatogram of the Test solutionis larger or more intense than the principal spot obtained from Standard solution B,and the sum of the intensities of the additional secondary spots obtained from the Test solutionis not more than 0.6%.

Mobile phase— Prepare a filtered and degassed mixture of methanol and water (7:3).Make adjustments,if necessary (see System Suitabilityunder Chromatography á621ñ).

Internal standard solution— Dissolve an accurately weighed quantity of ethylparaben in methanol,and dilute quantitatively,and stepwise if necessary,with methanol to obtain a solution containing about 0.19mg per mL.

Standard preparation— Dissolve an accurately weighed quantity of USP Quazepam RSin Internal standard solution,and dilute quantitatively,and stepwise if necessary,with Internal standard solutionto obtain a solution having a known concentration of about 1.5mg of quazepam per mL.

Assay preparation— Weigh and finely powder not fewer than 10Tablets.Transfer an accurately weighed portion of powder,equivalent to about 15mg of quazepam,to a 50-mLscrew-capped centrifuge tube.Add 10.0mLof Internal standard solution,and centrifuge for 30minutes.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L7.The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are about 0.4for ethylparaben and 1.0for quazepam,the resolution,R,between ethylparaben and quazepam is not less than 5.5,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 5µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of quazepam (C17H11ClF4N2S)in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Quazepam RSin the Standard preparation;and RUand RSare the ratios of the peak response of quazepam to that of ethylparaben obtained from the Assay preparationand the Standard preparation,respectively.