Assay—
[NOTE—Use low-actinic glassware.
] Transfer an accurately measured volume of Oral Solution, equivalent to about 50 mg of trifluoperazine, to a 250-mL separator with the aid of about 100 mL of water. Add 10 mL of sodium hydroxide solution (1 in 10), and extract with three 50-mL portions of cyclohexane. Wash the combined cyclohexane extracts with about 20 mL of water, and discard the water washing. Extract the combined cyclohexane extracts with four 50-mL portions of 0.1 N hydrochloric acid, collecting the aqueous extracts in a 500-mL volumetric flask. Dilute with 0.1 N hydrochloric acid to volume, and mix. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, dilute with 0.1 N hydrochloric acid to volume, and mix. Concomitantly determine the absorbances of this solution and of a Standard solution of
USP Trifluoperazine Hydrochloride RS in the same medium having a known concentration of about 12 µg per mL in 1-cm cells at 278 nm and at the wavelength of maximum absorbance at about 255 nm, with a suitable spectrophotometer, using 0.1 N hydrochloric acid as the blank. Calculate the quantity, in mg, of trifluoperazine (C
21H
24F
3N
3S) in each mL of the Oral Solution taken by the formula:
(407.51/480.43)(5
C/V)(
A255 
A278)
U / (
A255 A278)
S,
in which 407.51 and 480.43 are the molecular weights of trifluoperazine and trifluoperazine hydrochloride, respectively;
C is the concentration, in µg per mL, of
USP Trifluoperazine Hydrochloride RS in the Standard solution;
V is the volume, in mL, of Oral Solution taken; and the parenthetic expressions are the differences in the absorbances of the two solutions at the wavelengths indicated by the subscripts, for the assay solution (
U) and the Standard solution (
S), respectively.
Trifluoperazine Hydrochloride Syrup
11
—
USP Trifluoperazine Hydrochloride RS.