A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

Test solution: 5 mg per mL, in dimethylformamide.

(Official January 1, 2007)

0.005 M Monobasic sodium phosphate solution— Dissolve monobasic sodium phosphate in water to obtain a solution containing 690 µg per mL.

Mobile phase— Prepare a mixture of 0.005 M Monobasic sodium phosphate solution, acetonitrile, and tetrahydrofuran (62:37:1), filter through a 0.45-µm solvent-resistant filter, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Triamcinolone Diacetate RS in Mobile phase, and dilute quantitatively with Mobile phase to obtain a solution having a known concentration of about 40 µg per mL.

Assay preparation— Transfer about 50 mg of Triamcinolone Diacetate, accurately weighed, to a 50-mL volumetric flask, dissolve in Mobile phase, dilute with Mobile phase to volume, and mix. Pipet 2 mL of this solution into a second 50-mL volumetric flask, dilute with Mobile phase to volume, and mix.

System suitability preparation— Dissolve suitable quantities of USP Triamcinolone Diacetate RS and propylparaben in Mobile phase to obtain a solution containing about 40 µg per mL and 15 µg per mL, respectively.

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 1 mL per minute. Chromatograph the System suitability preparation, and record the peak responses as directed for Procedure: the relative retention times are 1.0 for triamcinolone diacetate and about 1.1 for propylparaben, the resolution, R, between the triamcinolone diacetate and propylparaben peaks is not less than 1.7, and the tailing factor, T, for the analyte peak is not more than 1.5. Chromatograph replicate injections of the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, and measure the area responses for the major peaks. Calculate the quantity, in mg, of C25H31FO8 in the portion of Triamcinolone Diacetate taken by the formula: in which C is the concentration, in µg per mL, of USP Triamcinolone Diacetate RS in the Standard preparation, and rU and rS are the peak area responses obtained from the Assay preparation and the Standard preparation, respectively.