A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Test solution: 2mg per mL,in dimethylformamide.

Mobile phase— Prepare a degassed solution containing about 60volumes of methanol and 40volumes of water such that the retention times for triamcinolone and hydrocortisone are about 5and 10minutes,respectively.

Internal standard solution— Dissolve hydrocortisone in Mobile phaseto obtain a solution having a concentration of about 0.3mg per mL.

Standard preparation— Transfer about 10mg of USP Triamcinolone RS,accurately weighed,to a 50-mLvolumetric flask,dissolve in Internal standard solution,dilute with the same solvent to volume,and mix.

Assay preparation— Using about 10mg of Triamcinolone,accurately weighed,prepare as directed under Standard preparation.

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 1.5mLper 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 2.0%,and the resolution factor between triamcinolone and hydrocortisone is not less than 3.0.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph by means of a suitable microsyringe or sampling valve,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C21H27FO6in the portion of Triamcinolone taken by the formula: in which Cis the concentration,in mg per mL,of USP Triamcinolone RSin the Standard preparation,and RUand RSare the peak response ratios of triamcinolone to hydrocortisone obtained from the Assay preparationand the Standard preparation,respectively.