Assay—
[NOTE—Use low-actinic glassware.
]Transfer a volume of Injection,equivalent to about 50mg of promazine hydrochloride,to a 100-mLvolumetric flask,dilute with 0.1Nhydrochloric acid to volume,and mix.Transfer 10.0mLof the solution to a 250-mLseparator,add 20mLof water,render alkaline with ammonium hydroxide,and extract with four 25-mLportions of ether.Extract the combined ether extracts with five 15-mLportions of 0.1Nhydrochloric acid,collecting the aqueous extracts in a 100-mLvolumetric flask.Aerate to remove residual ether,dilute with 0.1Nhydrochloric acid to volume,and mix.Without delay,concomitantly determine the absorbances of this solution and of a Standard solution of
USP Promazine Hydrochloride RSin the same medium having a known concentration of about 50µg per mLin 1-cm cells at the wavelength of maximum absorbance at about 301nm,with a suitable spectrophotometer,using 0.1Nhydrochloric acid as the blank.Calculate the quantity,in mg,of C
17H
20N
2S·HCl in each mLof the Injection taken by the formula:
(C/V)(AU/AS),
in which
Cis the concentration,in µg per mL,of
USP Promazine Hydrochloride RSin the Standard solution,
Vis the volume,in mL,of Injection taken,and
AUand
ASare the absorbances of the solution from the Injection and the Standard solution,respectively.