Medium: 0.5%of sodium lauryl sulfate solution;1000mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Standard solution— Dissolve a suitable quantity of USP Cortisone Acetate RS,accurately weighed,in the Dissolution Mediumto obtain a solution having a known concentration of about 5.55µg of cortisone acetate per mL.

Procedure— Determine the amount of C23H30O6in solution on filtered portions of the Dissolution Medium,suitably diluted,in 1-cm cells,at the wavelength of maximum absorbance at about 242nm in comparison with the Standard solution.

Tolerances— Not less than 75%(Q)of the labeled amount of C23H30O6is dissolved in 45minutes.

Mobile phase ,Internal standard solution,Standard preparation,Resolution solution,and Chromatographic system—Proceed as directed in the Assay.

Test solution— Place 1Tablet in a stoppered,50-mLconical flask,deposit 0.25mLof water on the tablet,insert the stopper in the flask,and allow to stand for 30minutes.Add 2.5mLof isopropyl alcohol,and place the unstoppered flask on a steam bath.Boil gently,if necessary,until the tablet disintegrates,then evaporate the solvent with the aid of a current of air.Remove from the steam bath,add 10.0mLof Internal standard solutionfor each 5mg of cortisone acetate declared,insert the stopper,and sonicate vigorously for 10minutes.Proceed as directed for the Assay preparation,beginning with “Filter a portion”,to obtain the Test solution.

Procedure— Proceed as directed in the Assaybut to chromatograph the Test solutioninstead of the Assay preparation.Calculate the quantity,in mg,of cortisone acetate (C23H30O6)in each Tablet taken by the formula: in which Wis the weight,in mg,of USP Cortisone Acetate RStaken for the Standard preparation;Vis the volume,in mL,of Internal standard solutionadded to the Test solution;and the other terms are as defined therein.

Mobile phase— Prepare a filtered and degassed mixture of n-butyl chloride,water-saturated n-butyl chloride,tetrahydrofuran,methanol,and glacial acetic acid (95:95:14:7:6).Make adjustments if necessary (seeSystem Suitabilityunder Chromatography á621ñ).

Internal standard solution— Prepare a solution of methylparaben in Mobile phasehaving a concentration of about 0.04mg per mL.

Standard preparation— Transfer about 12mg of USP Cortisone Acetate RS,accurately weighed,to a glass-stoppered,50-mLconical flask,add 25.0mLof Internal standard solution,and sonicate for 5minutes.Combine approximately 1mLof this solution with 3mLof Mobile phaseto obtain the Standard preparation.

Resolution solution— Dissolve a quantity of hydrocortisone acetate in the Standard preparationto obtain a solution containing about 0.1mg of hydrocortisone acetate per mL.

Assay preparation— Accurately weigh,then finely powder,not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 12mg of cortisone acetate,to a stoppered conical flask.Add 25.0mLof Internal standard solution,insert the stopper in the flask,and sonicate vigorously for 5minutes.Pass a portion through a polytef syringe filter,then combine approximately 1mLof the filtrate and 3mLof Mobile phaseto obtain the Assay preparation.

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 L3.The flow rate is about 1mLper minute.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the resolution,R,between cortisone acetate and hydrocortisone acetate is not less than 2.2(if necessary,add equal parts of n-butyl chloride and water-saturated n-butyl chloride to the Mobile phaseto meet this requirement).Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are 0.7for methylparaben and 1.0for cortisone acetate;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 15µL)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 cortisone acetate (C23H30O6)in the portion of Tablets taken by the formula: in which Wis the weight,in mg,of USP Cortisone Acetate RStaken for the Standard preparation;and RUand RSare the peak response ratios of cortisone acetate to the internal standard obtained from the Assay preparationand the Standard preparation,respectively.