note—Throughout the following procedures, protect test or assay specimens, the Reference Standard, and solutions containing them, by conducting the procedures without delay, under subdued light, or using low-actinic glassware.

A: Place a volume of Injection, equivalent to about 100 mg of triflupromazine hydrochloride, in a test tube, add 5 mL of 8 N nitric acid, and mix: a peach to amber color develops, quickly turns dark brown, and then changes to a clear solution having a yellow tint.

B: A volume of Injection, equivalent to about 50 mg of triflupromazine hydrochloride, meets the requirements under Identification—Organic Nitrogenous Bases 181.

C: The UV absorption spectrum of the Assay preparation, prepared as directed in the Assay, exhibits maxima and minima at the same wavelengths as that of the Standard preparation, prepared as directed in the Assay.

Standard preparation— Transfer about 50 mg of USP Triflupromazine Hydrochloride RS, accurately weighed, to a 50-mL volumetric flask, dissolve in 0.5 N sulfuric acid, dilute with 0.5 N sulfuric acid to volume, and mix. Proceed as directed under Assay preparation, beginning with “Transfer 10.0 mL of this solution to a 100-mL volumetric flask.” The concentration of USP Triflupromazine Hydrochloride RS in the Standard preparation is about 5 µg per mL.

Assay preparation— Transfer an accurately measured volume of Injection, equivalent to about 50 mg of triflupromazine hydrochloride, to a 50-mL volumetric flask, dilute with 0.5 N sulfuric acid to volume, and mix. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, dilute with the same acid to volume, and mix. Transfer 10.0 mL of this solution to a glass-stoppered, 50-mL centrifuge tube containing 10 mL of ether previously chilled in an ice bath, insert the stopper, shake for 3 minutes, and centrifuge at 1500 rpm for 5 minutes. Transfer 5.0 mL of the aqueous layer to a 100-mL volumetric flask, dilute with 0.5 N sulfuric acid to volume, and mix.

Procedure— Concomitantly determine the absorbances of the Assay preparation and the Standard preparation in 1-cm cells at the wavelength of maximum absorbance at about 255 nm, with a suitable spectrophotometer, using 0.5 N sulfuric acid as the blank. Calculate the quantity, in mg, of C18H19F3N2S·HCl in each mL of the Injection taken by the formula: in which C is the concentration, in µg per mL, of USP Triflupromazine Hydrochloride RS in the Standard preparation, V is the volume, in mL, of Injection taken, and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.