Mobile phase— Proceed as directed in the Assay under Sulfinpyrazone Capsules.

Acetate buffer— Transfer 240 mL of 0.1 N acetic acid to a 1-liter flask. Add 200 mL of 0.1 N potassium hydroxide, mix, and dilute with water to volume. Adjust to a pH of 5.0.

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

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

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

Chromatographic system (see Chromatography 621)—Proceed as directed in the Assay under Sulfinpyrazone Capsules. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the retention time for sulfinpyrazone is between 4.0 and 4.6 minutes, 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 10 µL) of the Standard preparation and the Test preparation into 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 preparation is 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%).