Assay
[NOTEUse low-actinic glassware.
]Transfer an accurately measured volume of Injection,equivalent to about 20mg of trifluoperazine,to a 250-mLseparator.Add 10mLof 4Nsulfuric acid,and extract with three 25-mLportions of carbon tetrachloride.Discard the carbon tetrachloride after each extraction.Add 10mLof ammonium hydroxide,and extract with five 40-mLportions of cyclohexane.Extract the combined cyclohexane extracts with five 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 25.0mLof 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 maximum 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 Injection taken by the formula:
(407.51/480.43)(2C/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 Injection 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.