Mobile phase— Proceed as directed in the Assayunder Sulfinpyrazone Capsules.

Acetate buffer— Transfer 240mLof 0.1Nacetic acid to a 1-liter flask.Add 200mLof 0.1Npotassium hydroxide,mix,and dilute with water to volume.Adjust to a pHof 5.0.

Diluting solution— Prepare a mixture of acetonitrile and Acetate buffer(4:1).

Standard preparation— Dissolve an accurately weighed quantity of USP Sulfinpyrazone RSin Diluting solution,and dilute quantitatively,and stepwise if necessary,with Diluting solutionto obtain a solution having a known concentration of about 10µg per mL.

Test preparation— Prepare a solution of Sulfinpyrazone in Diluting solutionhaving a known concentration of about 2mg per mL.

Chromatographic system (see Chromatography á621ñ)—Proceed as directed in the Assayunder Sulfinpyrazone Capsules.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the retention time for sulfinpyrazone is between 4.0and 4.6minutes,the tailing factor is not more than 2.0,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Test preparationinto the chromatograph,record the chromatograms,and measure the responses for all of the peaks:the sum of the peak responses,other than that of the sulfinpyrazone peak,from the Test preparationis not more than four times the sulfinpyrazone peak response from the Standard preparation(2.0%),and no single peak response is greater than twice the sulfinpyrazone peak response from the Standard preparation(1.0%).

Solvent— Use dimethyl sulfoxide.