A: Place an amount of finely powdered Tablets,equivalent to about 10mg of clonazepam,in a 125-mLseparator.Add 25mLof water,shake for 2minutes,and extract with two 40-mLportions of chloroform.Pass the extracts through anhydrous sodium sulfate,combine them,and evaporate at room temperature with the aid of a stream of nitrogen to dryness.Wash the residue with three 10-mLportions of solvent hexane:the IRabsorption spectrum of a potassium bromide dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Clonazepam RS.

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

Medium: degassed water;900mL.

Apparatus 2: 75rpm.

Time: 45minutes.

Mobile phase— Prepare a filtered and degassed mixture of water,methanol,and acetonitrile (40:30:30).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard solution— Prepare a solution of USP Clonazepam RSin methanol having a known concentration of about 0.05mg per mL.Quantitatively dilute a portion of this solution with Dissolution Mediumto obtain a Standard solutionhaving a known concentration similar to the expected concentration in the solution under test.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4-mm ×30-cm column that contains packing L1.The flow rate is about 1mLper minute.Chromatograph replicate injections of the Standard solution,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 2.0%;and the tailing factor is not more than 2.0.

Procedure— Separately inject equal volumes (about 100µL)of the Standard solutionand the solution under test into the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity of C15H10ClN3O3dissolved by comparison of the peak responses obtained from the Standard solutionand the test solution.

Tolerances— Not less than 75%(Q)of the labeled amount of C15H10ClN3O3is dissolved in 45minutes.

Buffer solution,Mobile phase,Diluent,System suitability solution,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Clonazepam.

Test preparation— Use the Assay preparation.

Procedure— Inject a volume (about 50µL)of the Test preparationinto the chromatograph,record the chromatogram,and measure the responses for all of the peaks.Calculate the percentage of each impurity in the portion of Tablets taken by the formula: in which Pis the relative response factor,which is 2.45for the peak with a relative retention time of 0.7(if present),1.84for clonazepam related compound A,0.94for clonazepam related compound B,and 1for all other impurities;riis the peak response for each impurity obtained from the Test preparation;and rCis the peak response for clonazepam in the Test preparation:not more than 0.8%for the peak at relative retention time 0.7,not more than 0.4%of clonazepam related compound A,and not more than 1.0%of clonazepam related compound Bare found;not more than 0.2%of any other impurity is found;and the sum of all other impurities is not more than 0.5%.

Buffer solution,Mobile phase,Diluent,Standard preparation,System suitability solution,and Chromatographic system— Proceed as directed in the Assayunder Clonazepam.

Assay preparation— Weigh and finely powder not fewer than 10Tablets.Transfer an accurately weighed amount of powder,equivalent to about 10mg of clonazepam,to a 100-mLvolumetric flask;dissolve,with sonication,in 75mLof Diluent;cool to room temperature,dilute with Diluentto volume,mix,and filter,discarding the first few mLof the filtrate.

Procedure— Separately inject equal volumes (about 50µL)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 clonazepam (C15H10ClN3O3)in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Clonazepam RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.