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 SYRUP PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

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

Acid-alcohol solutionand Palladium chloride solution— Prepare as directed in the Assayunder Perphenazine Injection.

Standard preparation— Dissolve an accurately weighed quantity of USP Perphenazine RSin Acid-alcohol solutionto obtain a solution having a known concentration of about 160µg per mL.

Assay preparation— Transfer an accurately measured volume of Syrup,equivalent to about 6mg of perphenazine,to a 25-mLvolumetric flask,dilute with water to volume,and mix.Transfer 10mLto a 125-mLseparator,add 25mLof water,adjust with ammonium hydroxide to a pHof 10to 11,and extract with four 20-mLportions of chloroform,filtering the extracts through anhydrous sodium sulfate.Evaporate the combined extracts on a steam bath with the aid of a stream of nitrogen to about 5mL.Complete the evaporation without application of heat,and dissolve the residue in 15.0mLof Acid-alcohol solution,filtering if necessary.

Procedure— Mix 10.0mLeach of the Assay preparationand the Standard preparationwith 15.0mLof Palladium chloride solution,filter if necessary,and concomitantly determine the absorbances of these solutions,against a reagent blank,in 1-cm cells at the wavelength of maximum absorbance at about 480nm,with a suitable spectrophotometer.Calculate the quantity,in mg,of perphenazine (C21H26ClN3OS)in each mLof the Syrup taken by the formula: in which Cis the concentration,in µg per mL,of USP Perphenazine RSin the Standard preparation;Vis the volume,in mL,of Syrup taken;and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.