A: Place a number of Tablets, equivalent to about 100 mg of flurbiprofen, in a flask, add 10 mL of 0.1 N hydrochloric acid, and sonicate until the Tablets disintegrate. Extract with two 15-mL portions of ether, combining the ether extracts in a flask containing about 1 g of anhydrous sodium sulfate. Decant the ether, and evaporate to dryness: the IR absorption spectrum of a mineral oil dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Flurbiprofen RS.

B: The retention time of the flurbiprofen peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

pH 7.2 Phosphate buffer— Dissolve 245 g of monobasic potassium phosphate and 50 g of sodium hydroxide in water to make 2000 mL of solution. Dilute 333 mL of this stock solution to 6000 mL with water. If necessary, adjust with 5 N sodium hydroxide or with phosphoric acid to a pH of 7.20 ± 0.05.

Medium: pH 7.2 phosphate buffer; 900 mL.

Apparatus 2: 50 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C15H13FO2 dissolved from UV absorbances at the wavelength of maximum absorbance at about 247 nm on filtered portions of the solution under test, suitably diluted with Dissolution Medium, in comparison with a Standard solution having a known concentration of USP Flurbiprofen RS in the same Medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C15H13FO2 is dissolved in 45 minutes.

Procedure for content uniformity— Proceed as directed in the Assay, except in preparing the Assay preparation to use 1 Tablet and to use 10.0 mL of Internal standard solution for each 25 mg of flurbiprofen in the Tablet, based on the labeled amount.

(Official January 1, 2007)

Mobile phase— Dissolve 1.4 g of monobasic sodium phosphate in 570 mL of water, add 430 mL of acetonitrile, and adjust with phosphoric acid to a pH of 3.0. Filter and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).

Internal standard solution— Dissolve acetophenone in Mobile phase to obtain a solution having a concentration of about 0.8 µL per mL.

Standard preparation— Accurately weigh about 30 mg of USP Flurbiprofen RS. Add 10.0 mL of Internal standard solution, and swirl to dissolve. This stock solution contains about 3 mg of USP Flurbiprofen RS per mL. Dilute a portion of this stock solution with 20 volumes of Mobile phase, and mix.

Assay preparation— Place 3 Tablets in a stoppered container. Based on the labeled amount, in mg, of flurbiprofen in each Tablet, add 25.0 mL of Internal standard solution for each 75 mg of flurbiprofen in the 3 Tablets. Shake by mechanical means for about 15 minutes, and centrifuge. Dilute a portion of this solution with 20 volumes of Mobile phase, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 25-cm column containing packing L7. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the responses as directed for Procedure: the relative retention times are about 0.4 for acetophenone and 1.0 for flurbiprofen; the resolution, R, between the acetophenone and flurbiprofen is not less than 8; and the relative standard deviation for replicate injections is not more than 2.0%.

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 flurbiprofen (C15H13FO2) in the portion of Tablets taken by the formula: in which W is the quantity, in mg, of USP Flurbiprofen RS used to prepare the Standard preparation; V is the volume, in mL, of Internal standard solution used to prepare the Assay preparation; and RU and RS are the ratios of the flurbiprofen peak response to the acetophenone peak response obtained from the Assay preparation and the Standard preparation, respectively.