A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Solution: 1in 100,000.

Medium: a mixture of methanol and water (3:1).

Test solution: 10mg per mL,in dehydrated alcohol.

pH3.5Buffer— Dissolve 68.0g of monobasic potassium phosphate in 1000mLof water,and adjust with phosphoric acid to a pHof 3.5±0.05.

Mobile phase— Prepare a suitable filtered and degassed mixture of water,acetonitrile,and pH3.5buffer(55:43:2).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

System suitability solution— Prepare a solution in Mobile phasecontaining about 0.01mg per mLof USP Ketoprofen RSand 0.005mg per mLof 3-benzoylbenzoic acid.[NOTE—Protect this solution from light.]

Standard solution— Dissolve an accurately weighed quantity of USP Ketoprofen RSquantitatively in Mobile phaseto obtain a solution having a known concentration of about 0.002mg per mL.[NOTE—Protect this solution from light.]

Test solution— Transfer about 100mg of Ketoprofen,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with Mobile phaseto volume,and mix.[NOTE—Protect this solution from light.]

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 233-nm detector and a 4.6-mm ×15-cm column that contains 3-µm packing L1.The flow rate is about 1.0mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.8for 3-benzoylbenzoic acid and 1.0for ketoprofen;the resolution,R,between 3-benzoylbenzoic acid and ketoprofen is not less than 4;the column efficiency,determined from the ketoprofen peak,is not less than 2250theoretical plates;and the tailing factor for the ketoprofen peak is not more than 2.0.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 5%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,run the chromatograph for seven times the retention time for ketoprofen,record the chromatograms,and measure the areas for the peaks.Calculate the percentage of each impurity by the same formula: in which Cis the concentration,in mg per mL,of USP Ketoprofen RSin the Standard solution;Wis the weight,in mg,of Ketoprofen taken to prepare the Test solution;riis the response of each individual peak,other than the main ketoprofen peak,obtained from the Test solution;and rSis the response of the main ketoprofen peak obtained from the Standard solution:not more than 0.2%of any individual impurity is found,and the sum of all impurities found is not more than 1.0%.