A: Place a number of Tablets,equivalent to about 100mg of flurbiprofen,in a flask,add 10mLof 0.1Nhydrochloric acid,and sonicate until the Tablets disintegrate.Extract with two 15-mLportions of ether,combining the ether extracts in a flask containing about 1g of anhydrous sodium sulfate.Decant the ether,and evaporate to dryness:the IRabsorption spectrum of a mineral oil dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Flurbiprofen RS.

B: The retention time of the flurbiprofen peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

pH7.2Phosphate buffer— Dissolve 245g of monobasic potassium phosphate and 50g of sodium hydroxide in water to make 2000mLof solution.Dilute 333mLof this stock solution to 6000mLwith water.If necessary,adjust with 5Nsodium hydroxide or with phosphoric acid to a pHof 7.20±0.05.

Medium: pH7.2phosphate buffer;900mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Procedure— Determine the amount of C15H13FO2dissolved from UVabsorbances at the wavelength of maximum absorbance at about 247nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,in comparison with a Standard solution having a known concentration of USP Flurbiprofen RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C15H13FO2is dissolved in 45minutes.

Procedure for content uniformity— Proceed as directed in the Assay,except in preparing the Assay preparationto use 1Tablet and to use 10.0mLof Internal standard solutionfor each 25mg of flurbiprofen in the Tablet,based on the labeled amount.

Mobile phase— Dissolve 1.4g of monobasic sodium phosphate in 570mLof water,add 430mLof acetonitrile,and adjust with phosphoric acid to a pHof 3.0.Filter and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Internal standard solution— Dissolve acetophenone in Mobile phaseto obtain a solution having a concentration of about 0.8µLper mL.

Standard preparation— Accurately weigh about 30mg of USP Flurbiprofen RS.Add 10.0mLof Internal standard solution,and swirl to dissolve.This stock solution contains about 3mg of USP Flurbiprofen RSper mL.Dilute a portion of this stock solution with 20volumes of Mobile phase,and mix.

Assay preparation— Place 3Tablets in a stoppered container.Based on the labeled amount,in mg,of flurbiprofen in each Tablet,add 25.0mLof Internal standard solutionfor each 75mg of flurbiprofen in the 3Tablets.Shake by mechanical means for about 15minutes,and centrifuge.Dilute a portion of this solution with 20volumes of Mobile phase,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm ×25-cm column containing packing L7.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the responses as directed for Procedure:the relative retention times are about 0.4for acetophenone and 1.0for flurbiprofen;the resolution,R,between the acetophenone and flurbiprofen is not less than 8;and the relative 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 flurbiprofen (C15H13FO2)in the portion of Tablets taken by the formula: in which Wis the quantity,in mg,of USP Flurbiprofen RSused to prepare the Standard preparation;Vis the volume,in mL,of Internal standard solutionused to prepare the Assay preparation;and RUand RSare the ratios of the flurbiprofen peak response to the acetophenone peak response obtained from the Assay preparationand the Standard preparation,respectively.