Standard preparation
Dissolve an accurately weighed quantity of
USP Triamcinolone Acetonide RSin
Internal standard solutionto obtain a solution having a known concentration of about 75µg per mL.Mix an accurately measured volume of the resulting solution with an equal volume of
Mobile phaseto obtain a
Standard preparationcontaining about 37.5µg of
USP Triamcinolone Acetonide RSper mL.
Procedure
Introduce equal volumes (between 15µLand 25µL)of the
Assay preparationand the
Standard preparationinto a high-pressure liquid chromatograph (see
Chromatography á621ñ)operated at room temperature,by means of a suitable microsyringe or sampling valve.Adjust the operating parameters with
Mobile phaseon the column so that the separation of triamcinolone acetonide and internal standard is optimized,with a retention time of about 14.5minutes for triamcinolone acetonide.Typically,the apparatus is fitted with a 4-mm ×30-cm column containing packing L1and is equipped with a UVdetector capable of monitoring absorbance at 254nm,and a suitable recorder.In a suitable chromatogram,the coefficient of variation for five replicate injections of a single specimen is not more than 3.0%;and the resolution factor,
R(see
Chromatography á621ñ),between the peaks for triamcinolone acetonide and fluoxymesterone is not less than 2.0.Measure the heights of the internal standard and triamcinolone acetonide peaks at the same retention times obtained from the
Assay preparationand the
Standard preparation.Calculate the quantity,in mg,of C
24H
31FO
6in the portion of Triamcinolone Acetonide taken by the formula:
1000C(RU/RS),
in which
Cis the concentration,in mg per mL,of
USP Triamcinolone Acetonide RSin the
Standard preparation;and
RUand
RSare the ratios of the peak heights of triamcinolone acetonide to the internal standard obtained from the
Assay preparationand the
Standard preparation,respectively.