A: Infrared Absorption 197K—Dissolve in methanol, evaporate the methanol on a steam bath, and dry at 105 for 30 minutes.

B: Ultraviolet Absorption 197U—

Test solution: 10 mg per mL, in dioxane.

Solution A— Prepare a filtered and degassed mixture of water and acetonitrile (7:3). Make adjustments if necessary (see System Suitability under Chromatography 621).

Solution B— Prepare a filtered and degassed mixture of acetonitrile and water (7:3). Make adjustments if necessary (see System Suitability under Chromatography 621).

Mobile phase— Use variable mixtures of Solution A and Solution B as 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 RS in Diluting solution, and dilute quantitatively, and stepwise if necessary, with Diluting solution to obtain a solution having a known concentration of about 20 µg per mL.

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

Chromatographic system (see Chromatography 621)— 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 1 mL per 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 15 µL) of the Standard solution and the Test solution into 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 C is the concentration, in mg per mL, of USP Cortisone Acetate RS in the Standard solution; W is the amount, in mg, of Cortisone Acetate taken for the Test solution; ri is the response for each impurity; and rS is 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.

(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of water and acetonitrile (550:450). Make adjustments if necessary (see System Suitability under Chromatography 621).

pH 4 Buffer solution— Transfer 20 mL of 1 N hydrochloric acid, 150 mL of 0.5 N potassium chloride, and 50 mL of 0.5 M sodium acetate to a 1-L volumetric flask, dilute with water to volume, and mix.

Diluent solution— Prepare a mixture of acetonitrile and pH 4 Buffer solution (1:1).

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

Assay preparation— Using about 25 mg of Cortisone Acetate, accurately weighed, proceed as directed for Standard preparation.

Chromatographic system (see Chromatography 621)— 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 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 1500 theoretical 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 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C23H30O6 in the portion of Cortisone Acetate taken by the formula: in which C is the concentration, in mg per mL, of USP Cortisone Acetate RS in the Standard preparation; and rU and rS are the cortisone acetate peak responses obtained from the Assay preparation and the Standard preparation, respectively.