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 16 mg of perphenazine, to a 200-mL volumetric flask, dissolve in and dilute with methanol to volume, mix, and filter.

Procedure— Inject a volume (about 10 µL) of the Test preparation into 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 ri is the peak response of perphenazine sulfoxide (relative retention time of about 0.72); and rs is the sum of the responses of all the peaks: not more than 5.0% of perphenazine sulfoxide is found.

(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of 0.01 M ammonium acetate, acetonitrile, and methanol (48:39:13). Adjust with glacial acetic acid to a pH of 4.5. Make adjustments if necessary (see System Suitability under Chromatography 621).

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

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

Assay preparation— Transfer an accurately measured portion of Oral Solution, equivalent to about 16 mg of perphenazine, to a 200-mL volumetric 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 8.0 µg per mL, and filter.

Chromatographic system (see Chromatography 621)— 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 1.5 mL per minute. Chromatograph the Resolution solution, and record the peak responses as directed for Procedure: the relative retention times are about 0.6 for brompheniramine and 1.0 for 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 10 µL) of the Standard preparation and the Assay preparation into 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 C is the concentration, in mg per mL, of USP Perphenazine RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.