NOTE—Throughout the following procedures,protect test or assay specimens,the USP Reference Standard,and solutions containing them,by conducting the procedures without delay,under subdued light,or using low-actinic glassware.

FOR ORAL SOLUTION PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

FOR ORAL SOLUTION PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.

Mobile phase,Resolution solution,Standard preparation,and Chromatographic system— Proceed as directed in the Assay.

Test preparation— Transfer an accurately measured portion of Oral Solution,equivalent to about 16mg of perphenazine,to a 200-mLvolumetric flask,dissolve in and dilute with methanol to volume,mix,and filter.

Procedure— Inject a volume (about 10µL)of the Test preparationinto the chromatograph,record the chromatogram,and measure the peak responses.Calculate the percentage of perphenazine sulfoxide in the portion of Oral Solution taken by the formula: in which riis the peak response of perphenazine sulfoxide (relative retention time of about 0.72);and rsis the sum of the responses of all the peaks:not more than 5.0%of perphenazine sulfoxide is found.

Mobile phase— Prepare a filtered and degassed mixture of 0.01Mammonium acetate,acetonitrile,and methanol (48:39:13).Adjust with glacial acetic acid to a pHof 4.5.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Resolution solution— Dissolve suitable quantities of brompheniramine maleate and USP Perphenazine RSin methanol to obtain a solution having known concentrations of about 40µg per mLand 8µg per mL,respectively.

Standard preparation— Dissolve an accurately weighed quantity of USP Perphenazine RSin methanol,dilute quantitatively,and stepwise if necessary,with methanol to obtain a solution having a known concentration of about 8.0µg per mL,and filter.

Assay preparation— Transfer an accurately measured portion of Oral Solution,equivalent to about 16mg of perphenazine,to a 200-mLvolumetric flask,dissolve in and dilute with methanol to volume,and mix.Dilute quantitatively,and stepwise if necessary,with methanol to obtain a solution having a concentration of about 8.0µg per mL,and filter.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×30-cm column that contains packing L11.The flow rate is about 1.5mLper minute.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.6for brompheniramine and 1.0for perphenazine;and the resolution,R,between brompheniramine and perphenazine is not less than 3.0.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the tailing factor is not more than 3.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)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 perphenazine (C21H26ClN3OS)in the portion of Oral Solution taken by the formula: in which Cis the concentration,in mg per mL,of USP Perphenazine RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.