Solution A,Solution B,Mobile phase,System suitability solution,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Amcinonide,except to use a 240-nm detector.

Assay preparation— Dissolve an accurately weighed quantity of Ointment in a suitable volume of a mixture of acetonitrile and chloroform (4:1)by heating in a hot water bath,cooling,and adjusting quantitatively with the same solvent mixture to obtain a solution having a concentration of about 0.2mg of amcinonide per mL.Cool to room temperature,dilute with acetonitrile to volume,and filter.Transfer 5mLof this solution to a 50-mLvolumetric flask,dilute with Solution Bto volume,and mix.

Procedure— Separately inject equal volumes (about 10µL)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 amcinonide (C28H35FO7)in the portion of Ointment taken by the formula: in which Cis the concentration,in mg per mL,of USP Amcinonide RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.