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

A: Place about 50 mg of Fluphenazine Decanoate and about 50 mg of USP Fluphenazine Decanoate Dihydrochloride RS in separate, glass-stoppered, small centrifuge tubes, and treat each tube as follows. Add 1.5 mL of sodium hydroxide solution (1 in 250), and mix. Add 2 mL of carbon disulfide, shake vigorously for 2 minutes, and centrifuge. Dry the lower, clear layer by filtering through 2 g of anhydrous sodium sulfate: the IR absorption spectrum of the test preparation, determined in a 0.1-mm cell, exhibits maxima only at the same wavelengths as that of the Standard preparation, similarly measured.

B: Use a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Impregnate the plate with a 1 in 20 solution of tetradecane in hexane, and allow to air-dry. Prepare a test solution in alcohol containing 20 mg per mL. Apply 1 µL each of the test solution and of a Standard solution of USP Fluphenazine Decanoate Dihydrochloride RS in alcohol, similarly prepared. Allow the spots to dry. Apply to the spot from the Standard solution, 1.0 µL of 0.1 N sodium hydroxide and allow it to dry. Develop the plate in an equilibrated chamber using a mixture of methanol and water (9:1) as the mobile phase. Examine the plate under short-wavelength UV light at 254 nm: the RF value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.

Test solution: methanol.

Standard solution: methanol.

Eluant : a mixture of acetone, cyclohexane, and ammonium hydroxide (16:6:1).

Visualization: 1; then spray the plate with 50% sulfuric acid.

Interpretation: no individual ordinary impurity observed exceeds 1.0% and the total of any ordinary impurities observed does not exceed 2.0%.