A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Test solution: 10mg per mL,in chloroform.

Standard solutions— Prepare a solution of USP Flunisolide RSin acetone to contain 10mg per mL(Standard solution A).Dilute 1mLof Standard solution Awith acetone to 100mL(Standard solution B).

Test preparation— Prepare a solution of Flunisolide in acetone to contain 10mg per mL.

Procedure— Apply 10-µLvolumes of Standard solution A,Standard solution B,and the Test preparationto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Place the plate in a suitable chromatographic chamber previously equilibrated with a mixture of toluene and alcohol (90:10),seal the chamber,and develop the chromatogram until the solvent front has moved three-fourths of the length of the plate.Remove the plate,allow the solvent to evaporate,and examine the plate under short-wavelength UVlight:the RFvalue of the principal spot obtained from the Test preparationcorresponds to that obtained from Standard solution A.No secondary spot exhibits an intensity greater than that of the principal spot from Standard solution B.

Solvent— Use dimethyl sulfoxide.

Mobile phase— Prepare a suitable degassed solution of water and acetonitrile (3:2)such that at an approximate flow rate of 1.6mLper minute,the retention time of Flunisolide is about 6minutes.

Standard preparation— Dissolve an accurately weighed quantity of USP Flunisolide RSin Mobile phaseto obtain a solution having a known concentration of about 0.2mg per mL.

Assay preparation— Using 20mg of Flunisolide,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 4-mm ×25-cm column that contains 5-to 10-µm packing L7.The flow rate is about 1.6mLper minute.Chromatograph the Standard preparation,and record the peak response as directed for Procedure:the column efficiency is not less than 2700theoretical plates;the tailing factor for the flunisolide peak is not more than 1.7;and the relative standard deviation for replicate injections is not more than 1.0%.

Procedure— Separately inject equal volumes (between 15µLand 30µL)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 C24H31FO6in the portion of Flunisolide taken by the formula: in which 434.51and 443.51are the molecular weights of C24H31FO6and C24H31FO6·½H2O,respectively;Cis the concentration,in mg per mL,of USP Flunisolide RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.