A: Infrared Absorption á197Kñ—Dissolve in methanol,evaporate the methanol on a steam bath,and dry at 105for 30minutes.

B:Ultraviolet Absorption á197Uñ—

Test solution: 10mg per mL,in dioxane.

Solution A— Prepare a filtered and degassed mixture of water and acetonitrile (7:3).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Solution B— Prepare a filtered and degassed mixture of acetonitrile and water (7:3).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Mobile phase— Use variable mixtures of Solution Aand Solution Bas directed for Chromatographic system.

Diluting solution— Prepare a filtered mixture of acetonitrile,water,and glacial acetic acid (7:3:0.1).

Standard solution— Dissolve an accurately weighed quantity of USP Cortisone Acetate RSin Diluting solution,and dilute quantitatively,and stepwise if necessary,with Diluting solutionto obtain a solution having a known concentration of about 20µg per mL.

Test solution— Transfer about 25mg of Cortisone Acetate,accurately weighed,to a 10-mLvolumetric flask,dissolve in and dilute with Diluting solutionto volume,sonicate,and mix.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×15-cm column that contains packing L1.The flow rate is about 1mLper minute.The chromatograph is programmed as follows. Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 5.0%.

Procedure— Separately inject equal volumes (about 15µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the peak responses.Calculate the percentage of each impurity in the portion of Cortisone Acetate taken by the formula: in which Cis the concentration,in mg per mL,of USP Cortisone Acetate RSin the Standard solution;Wis the amount,in mg,of Cortisone Acetate taken for the Test solution;riis the response for each impurity;and rSis the response of the major peak in the Standard solution:not more than 1.5%of any individual impurity is found;and not more than 2.0%of total impurities is found.

Mobile phase— Prepare a filtered and degassed mixture of water and acetonitrile (550:450).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

pH4Buffer solution— Transfer 20mLof 1Nhydrochloric acid,150mLof 0.5Npotassium chloride,and 50mLof 0.5Msodium acetate to a 1-Lvolumetric flask,dilute with water to volume,and mix.

Diluent solution— Prepare a mixture of acetonitrile and pH4Buffer solution(1:1).

Standard preparation— Transfer about 25mg of USP Cortisone Acetate RS,accurately weighed,to a 250-mLvolumetric flask.Add 100mLof Diluent solution,sonicate until a clear solution is obtained,and dilute with Diluent solutionto volume.

Assay preparation— Using about 25mg of Cortisone Acetate,accurately weighed,proceed as directed for 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 containing 10-µm packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 1500theoretical plates;the tailing factor is not more than 2.0;the capacity factor,k¢,is not less than 2.0;and the standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)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 C23H30O6in the portion of Cortisone Acetate taken by the formula: in which Cis the concentration,in mg per mL,of USP Cortisone Acetate RSin the Standard preparation;and rUand rSare the cortisone acetate peak responses obtained from the Assay preparationand the Standard preparation,respectively.