A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

Solution: 10 µg per mL.

Test solution: 10 mg per mL, in chloroform.

Mobile phase and Chromatographic system—Proceed as directed in the Assay.

Test preparation— Transfer about 25 mg of fluocinonide, accurately weighed, to a 10-mL volumetric flask, add acetonitrile to volume, and mix.

Procedure— Inject 30 µL of the Test preparation into the chromatograph, record the chromatogram, and measure the area responses of all peaks. Calculate the area percentage of each peak observed in the chromatogram. The largest secondary peak is not more than 1.0% of the total area, and no other secondary peak is more than 0.5% of the total area. The sum of the areas of all peaks, other than the main peak, does not constitute more than 2.0% of the total area.

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and water (1:1). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Transfer about 25 mg of USP Fluocinonide RS, accurately weighed, to a 100-mL volumetric flask, add acetonitrile to volume, and mix. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix to obtain a solution having a known concentration of about 0.025 mg of USP Fluocinonide RS per mL.

Assay preparation— Using about 25 mg of Fluocinonide, accurately weighed, proceed as directed for Standard 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 30 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 Fluocinonide taken by the formula: in which C is the concentration, in mg per mL, of USP Fluocinonide RS in the Standard preparation; and rU and rS are the peak responses due to the fluocinonide obtained from the Assay preparation and the Standard preparation, respectively.