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