A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Test solution: 5mg per mL,in dimethylformamide.

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

Mobile phase— Prepare a mixture of 0.005M 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 Suitabilityunder Chromatography á621ñ).

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

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

System suitability preparation— Dissolve suitable quantities of USP Triamcinolone Diacetate RSand propylparaben in Mobile phaseto obtain a solution containing about 40µg per mLand 15µg per mL,respectively.

Chromatographic system (see Chromatography á621ñ)—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 1mLper minute.Chromatograph the System suitability preparation,and record the peak responses as directed for Procedure:the relative retention times are 1.0for triamcinolone diacetate and about 1.1for 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 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,and measure the area responses for the major peaks.Calculate the quantity,in mg,of C25H31FO8in the portion of Triamcinolone Diacetate taken by the formula: in which Cis the concentration,in µg per mL,of USP Triamcinolone Diacetate RSin the Standard preparation,and rUand rSare the peak area responses obtained from the Assay preparationand the Standard preparation,respectively.