A: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparation,both relative to the internal standard,as obtained in the Assay.

B: Prepare a test solution of the Cream in acetonitrile containing 0.2mg per mLof mometasone furoate.Prepare a Standard solution of USP Mometasone Furoate RSin acetonitrile having the same concentration as the test solution.The test solution so obtained responds to the Thin-layer Chromatographic Identification Test á201ñ,a mixture of chloroform and ethyl acetate (3:1)being used as the developing solvent.

Mobile phase— Proceed as directed under the Assayfor Mometasone Furoate.

Internal standard solution— Dissolve a suitable quantity of beclomethasone dipropionate in acetonitrile to obtain a solution containing about 0.53mg per mL.

Standard preparation— Dissolve an accurately weighed quantity of USP Mometasone Furoate RSin acetonitrile,and dilute quantitatively,and stepwise if necessary,with acetonitrile to obtain a solution having a known concentration of about 0.136mg per mL.Pipet equal amounts of this solution and the Internal standard solution,and dilute quantitatively,and stepwise if necessary,with acetonitrile to obtain a solution having known concentrations of about 0.027mg of mometasone furoate and 0.106mg of beclomethasone dipropionate per mL.

Assay preparation— Transfer an accurately weighed portion of Cream,equivalent to about 2.0mg of mometasone furoate,to a 50-mLscrew-capped centrifuge tube.Pipet 15.0mLof Internal standard solutionand 15.0mLof acetonitrile into the tube,and attach the cap.Heat in an 85water bath until the cream completely melts,and shake by hand for 2minutes.Repeat the heating and shaking.Place the tube in an ice-methanol bath for 10minutes.Centrifuge to obtain a clear supernatant,and transfer 10.0mLof the supernatant layer into a 25-mLvolumetric flask.Dilute with acetonitrile to volume,and mix.

Chromatographic system (see Chromatography á621ñ)—Proceed as directed in the Assayunder Mometasone Furoate.

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 mometasone furoate (C27H30Cl2O6)in the portion of Cream taken by the formula: in which Cis the concentration,in mg per mL,of USP Mometasone Furoate RSin the Standard preparation,and RUand RSare the ratios of the mometasone furoate peak to the internal standard peak obtained from the Assay preparationand the Standard preparation,respectively.