A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Solution: 10µg per mL.

Medium: 0.1Nhydrochloric acid in isopropyl alcohol (10in 100).

Ratio: A267/A297,between 0.97and 1.03.

Test solution: chloroform.

Standard solution: chloroform.

Eluant: a mixture of chloroform,methanol,and methyl ethyl ketone (40:30:30).

Visualization: 1.

Buffer solution— Dissolve 7.1g of anhydrous dibasic sodium phosphate in about 800mLof water,adjust with phosphoric acid to a pHof 6.0±0.1,dilute with water to make 1000mLof solution,and mix.

Mobile phase— Prepare a suitable degassed and filtered mixture of Buffer solutionand methanol (60:40).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Transfer about 50mg of USP Suprofen RS,accurately weighed,to a 50-mLvolumetric flask,dilute with methanol to volume,and mix.Transfer 5.0mLof this solution to a 25-mLvolumetric flask,dilute with Buffer solutionto volume,and mix.Transfer 2.0mLof this solution to a 25-mLvolumetric flask,dilute with Buffer solutionto volume,and mix to obtain a solution having a known concentration of about 0.016mg per mL.

Assay preparation— Transfer about 50mg of Suprofen,accurately weighed,to a 50-mLvolumetric flask,dilute with methanol to volume,and mix.Transfer 5.0mLof this solution to a 25-mLvolumetric flask,dilute with Buffer solutionto volume,and mix.Transfer 2.0mLof this solution to a 25-mLvolumetric flask,dilute with Buffer solutionto volume,and mix.

Chromatographic system— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the analyte peak is not less than 500theoretical plates,the tailing factor for the peak is not more than 2.0,and the relative standard deviation for replicate injections is not more than 2%.

Procedure— [NOTE—Use peak areas where peak responses are indicated.]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 C14H12O3Sin the portion of Suprofen taken by the formula: in which Cis the concentration,in mg per mL,of USP Suprofen RSin the Standard preparation,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.