A: A quantity of finely powdered Tablets, equivalent to about 10 mg of tolmetin, responds to Identification test A under Tolmetin Sodium Capsules.

B: The chromatogram of the Assay preparation obtained as directed in the Assay exhibits a major peak for tolmetin, the retention time of which corresponds to that exhibited in the chromatogram of the Standard preparation obtained as directed in the Assay.

Medium , Apparatus, Time, and Procedure—Proceed as directed in the test for Dissolution under Tolmetin Sodium Capsules.

Tolerances— Not less than 75% (Q) of the labeled amount of C15H15NO3 is dissolved in 30 minutes.

(Official January 1, 2007)

pH 2.7 buffer solution, Mobile phase, Solvent mixture, Standard preparation, Resolution solution, and Chromatographic system— Prepare as directed in the Assay under Tolmetin Sodium Capsules.

Assay preparation— Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 60 mg of tolmetin, to a 100-mL volumetric flask. Add about 75 mL of Solvent mixture, and shake by mechanical means for 30 minutes. Dilute with Solvent mixture to volume, mix, and filter through a filter having a porosity of 0.45 µm or less.

Procedure— 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 C15H15NO3 in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Tolmetin Sodium RS in the Standard preparation, 257.29 and 279.27 are the molecular weights of tolmetin and anhydrous tolmetin sodium, respectively, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.