Assay—
[NOTE—Use low-actinic glassware.
] Transfer a volume of Injection, equivalent to about 50 mg of promazine hydrochloride, to a 100-mL volumetric flask, dilute with 0.1 N hydrochloric acid to volume, and mix. Transfer 10.0 mL of the solution to a 250-mL separator, add 20 mL of water, render alkaline with ammonium hydroxide, and extract with four 25-mL portions of ether. Extract the combined ether extracts with five 15-mL portions of 0.1 N hydrochloric acid, collecting the aqueous extracts in a 100-mL volumetric flask. Aerate to remove residual ether, dilute with 0.1 N hydrochloric acid to volume, and mix. Without delay, concomitantly determine the absorbances of this solution and of a Standard solution of
USP Promazine Hydrochloride RS in the same medium having a known concentration of about 50 µg per mL in 1-cm cells at the wavelength of maximum absorbance at about 301 nm, with a suitable spectrophotometer, using 0.1 N hydrochloric acid as the blank. Calculate the quantity, in mg, of C
17H
20N
2S·HCl in each mL of the Injection taken by the formula:
(C / V)(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Promazine Hydrochloride RS in the Standard solution,
V is the volume, in mL, of Injection taken, and
AU and
AS are the absorbances of the solution from the Injection and the Standard solution, respectively.
11
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USP Promazine Hydrochloride RS. USP Endotoxin RS.