A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

Solution: 10 µg per mL.

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

Ratio: A267 / A297, between 0.97 and 1.03.

Test solution: chloroform.

Standard solution: chloroform.

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

Visualization: 1.

(Official January 1, 2007)

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

Mobile phase— Prepare a suitable degassed and filtered mixture of Buffer solution and methanol (60:40). Make adjustments if necessary (see System Suitability under Chromatography 621).

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

Assay preparation— Transfer about 50 mg of Suprofen, accurately weighed, to a 50-mL volumetric flask, dilute with methanol to volume, and mix. Transfer 5.0 mL of this solution to a 25-mL volumetric flask, dilute with Buffer solution to volume, and mix. Transfer 2.0 mL of this solution to a 25-mL volumetric flask, dilute with Buffer solution to 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 2 mL per 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 500 theoretical 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 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C14H12O3S in the portion of Suprofen taken by the formula: in which C is the concentration, in mg per mL, of USP Suprofen RS in the Standard preparation, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.