Medium: pH7.0phosphate buffer (see Buffer Solutionsin the section Reagents,Indicators,and Solutions);1000mL.

Apparatus 1: 10-mesh basket;100rpm.

Time: 60minutes.

Procedure— Filter 20mLof the solution under test,and transfer 10.0mLof the filtrate to a 100-mLvolumetric flask.Dilute with Dissolution Mediumto volume,and mix.Determine the absorbances of this solution and a Standard solution prepared from USP Fenoprofen Sodium RS,in the same medium having a known concentration of about 60µg per mLat the wavelength of maximum absorbance at about 270nm,using Dissolution Mediumas the blank.Calculate the amount of C15H14O3dissolved,in mg,by the formula: in which 242.28is the molecular weight of fenoprofen;264.26is the molecular weight of anhydrous fenoprofen sodium;Cis the concentration of anhydrous fenoprofen sodium in the Standard solution,as determined from the concentration of USP Fenoprofen Sodium RScorrected for moisture content by a titrimetric water determination;and AUand ASare the absorbances of the solutions obtained from the substance under test and the USP Reference Standard,respectively.

Tolerances— Not less than 75%(Q)of the labeled amount of C15H14O3is dissolved in 60minutes.

Mobile phase,Diluting solution,Resolution solution,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Fenoprofen Calcium.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 6000mg of fenoprofen,to a 250-mLvolumetric flask,add 50mLof 0.5Nhydrochloric acid,and sonicate for 10minutes,shaking the solution occasionally.Dilute with acetone to volume,sonicate for 10minutes,and stir for an additional 30minutes.Transfer 5.0mLof this solution to a 200-mLvolumetric flask,dilute with Diluting solutionto volume,and mix.Pass a portion of this solution through a suitable filter having a 0.5-µm or finer porosity,discarding the first 8mLof the filtrate,and use the clear filtrate as the Assay preparation.

Procedure— Proceed as directed in the Assayunder Fenoprofen Calcium.Calculate the quantity,in mg,of fenoprofen (C15H14O3)in the portion of Tablets taken by the formula: in which 484.55is two times the molecular weight of fenoprofen;522.61is the molecular weight of fenoprofen calcium;and the other terms are as defined therein.