» Fluocinonide Gel contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of fluocinonide (C26H32F2O7).
Packaging and storage Preserve in collapsible tubes or tight containers.
USP Reference standards 11
Identification Weigh an amount of Gel, equivalent to about 2.5 mg of fluocinonide, into a glass-stoppered, 50-mL centrifuge tube containing 20 mL of sodium chloride solution (1 in 10). Add 5 mL of chloroform and 15 mL of methanol, and shake vigorously. Centrifuge to clarify the chloroform layer, and remove the solid material present at the interphase. Discard the upper phase. Dry a portion of the chloroform layer over anhydrous sodium sulfate. Using the dried extract as the Test preparation, proceed as directed in the Identification test under Fluocinonide Cream, beginning with Apply 10 µL of the Test solution.
Minimum fill 755: meets the requirements.
Mobile phase Prepare a mixture of acetonitrile and water (1:1). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation Dissolve an accurately weighed quantity of USP Fluocinonide RS in acetonitrile to obtain a solution having a known concentration of about 200 µg per mL. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, dilute with acetonitrile to volume, and mix. The final concentration is 20 µg per mL.
Assay preparation Transfer an accurately weighed quantity of Gel, containing about 2 mg of fluocinonide, to a 100-mL volumetric flask. Add about 60 mL of acetonitrile, and dissolve the gel by heating on a steam bath. Cool to room temperature, dilute with acetonitrile to volume, and mix. Centrifuge a portion at about 2500 rpm for about 5 minutes. Filter a portion of the centrifugate through an acetonitrile-insoluble membrane filter. The filtrate is the Assay preparation.
Chromatographic system (see Chromatography 621)The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 1.5%.
Procedure Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C26H32F2O7 in the portion of Gel taken by the formula:
0.1C(rU / rS)in which C is the concentration, in µg per mL, of USP Fluocinonide RS in the Standard preparation; and rU and rS are the peak responses due to fluocinonide obtained from the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 3228