USP Reference standards 
11
—
USP Perphenazine RS.
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.
Identification—
Add 10 mL of water to a volume of Syrup, equivalent to about 4 mg of perphenazine, render alkaline by dropwise addition of sodium hydroxide to a pH of 11 to 12, and extract with four 5-mL portions of chloroform, combining the extracts through a bed of anhydrous sodium sulfate in a funnel into a beaker. Evaporate the extracts on a steam bath nearly to dryness, and dissolve the residue in 4 mL of methanol: the solution so obtained responds to the
Identification test under
Perphenazine Injection.
Assay—
Acid-alcohol solution and Palladium chloride solution—
Prepare as directed in the
Assay under
Perphenazine Injection.
Standard preparation—
Dissolve an accurately weighed quantity of
USP Perphenazine RS in
Acid-alcohol solution to obtain a solution having a known concentration of about 160 µg per mL.
Assay preparation—
Transfer an accurately measured volume of Syrup, equivalent to about 6 mg of perphenazine, to a 25-mL volumetric flask, dilute with water to volume, and mix. Transfer 10 mL to a 125-mL separator, add 25 mL of water, adjust with ammonium hydroxide to a pH of 10 to 11, and extract with four 20-mL portions 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 5 mL. Complete the evaporation without application of heat, and dissolve the residue in 15.0 mL of Acid-alcohol solution, filtering if necessary.
Procedure—
Mix 10.0 mL each of the
Assay preparation and the
Standard preparation with 15.0 mL of
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 480 nm, with a suitable spectrophotometer. Calculate the quantity, in mg, of perphenazine (C
21H
26ClN
3OS) in each mL of the Syrup taken by the formula:
0.0375(C/V)(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Perphenazine RS in the
Standard preparation; V is the volume, in mL, of Syrup taken; and
AU and
AS are the absorbances of the solutions from the
Assay preparation and the
Standard preparation, respectively.
