Test solution: 10mg per mL,in chloroform.

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

Standard solution— Dissolve an accurately weighed quantity of triamcinolone acetonide in methanol,and dilute quantitatively,and stepwise if necessary,with methanol to obtain a solution having a known concentration of about 0.004mg per mL.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 10µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the responses for all of the peaks.Calculate the percentage of triamcinolone acetonide in the portion of Triamcinolone Hexacetonide taken by the formula: in which Cis the concentration,in mg per mL,of triamcinolone acetonide in the Standard solution,Dis the concentration,in mg per mL,of triamcinolone hexacetonide in the Test solution,and rUand rSare the peak responses for triamcinolone acetonide obtained from the Test solutionand the Standard solution,respectively:not more than 1.0%is found.

Mobile phase— Prepare a filtered and degassed mixture of methanol and water (75:25).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Triamcinolone Hexacetonide RSin methanol,and dilute quantitatively,and stepwise if necessary,with methanol to obtain a solution having a known concentration of about 0.4mg per mL.

System suitability solution— Dissolve suitable quantities of triamcinolone acetonide and USP Triamcinolone Hexacetonide RSin methanol to obtain a solution containing about 0.4mg per mLof each.

Assay preparation— Transfer about 40mg of Triamcinolone Hexacetonide,accurately weighed,to a 100-mLvolumetric flask.Dissolve in and dilute with methanol to volume,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.27for triamcinolone acetonide and 1.0for triamcinolone hexacetonide,the resolution,R,between triamcinolone acetonide and triamcinolone hexacetonide is not less than 7.5,the tailing factor for triamcinolone hexacetonide is not more than 1.3,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C30H41FO7in the portion of Triamcinolone Hexacetonide taken by the formula: in which Cis the concentration,in mg per mL,of USP Triamcinolone Hexacetonide RSin the Standard preparation,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.