A:Infrared Absorption á197Kñ.

B: The retention time of the major peak for verapamil in the chromatogram of the Test preparationcorresponds to that exhibited in the chromatogram of Standard preparation B,as obtained in the test forChromatographic purity.

C: It responds to the tests for Chloride á191ñ.

Aqueous solvent mixture— Prepare a 0.015Nsodium acetate solution containing about 33mLof glacial acetic acid per L.

Mobile phase— Prepare a filtered and degassed mixture ofAqueous solvent mixture,acetonitrile,and 2-aminoheptane (70:30:0.5).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparations— Dissolve an accurately weighed quantity ofUSP Verapamil Hydrochloride RSin Mobile phase,and dilute quantitatively,and stepwise if necessary,withMobile phaseto obtain Standard preparation Aand Standard preparation Bhaving known concentrations of about 5.6and 9.4µg per mL,respectively.

Test preparation— Prepare a solution of Verapamil Hydrochloride in Mobile phasehaving a known concentration of about 1.9mg per mL.

System suitability solution— Dissolve suitable quantities ofUSP Verapamil Hydrochloride RSand USP Verapamil Related Compound B RSin Mobile phaseto obtain a System suitability solutionhaving known concentrations of about 1.9and 1.5mg,respectively,in each mL.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 278-nm detector and a 4.6-mm ×12.5-to 15-cm column that contains packing L1.The flow rate is about 0.9mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.88for verapamil related compound Band 1.0for verapamil;the resolution,R,between the verapamil related compound Band verapamil peaks is not less than 1.5,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of Standard preparations Aand Band the Test preparationinto the chromatograph,and allow the Test preparationto elute for not less than four times the retention time for verapamil.Record the chromatograms,and measure all the peak responses.The sum of the peak responses,other than that of verapamil,from theTest preparationis not greater than the verapamil peak response obtained from Standard preparation B(0.5%);and no single peak response is greater than that of the verapamil peak response obtained from Standard preparation A(0.3%).

Solvent— Use 0.1%n-propanol in water.