(kee'' toe proe' fen).
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C16H14O3 254.28

Benzeneacetic acid, 3-benzoyl--methyl-, (±)-.
(±)-m-Benzoylhydratropic acid [22071-15-4].
» Ketoprofen contains not less than 98.5 percent and not more than 101.0 percent of C16H14O3, calculated on the dried basis.
Packaging and storage— Preserve in tight containers.
USP Reference standards 11
USP Ketoprofen RS Click to View Structure
USP Ketoprofen Related Compound D RS
Solution: 1 in 100,000.
Medium: a mixture of methanol and water (3:1).
Absorptivities at the wavelength of maximum absorbance at about 258 nm do not differ by more than 3.0%, calculated on the dried basis.
Melting range, Class I 741: between 92.0 and 97.0.
Specific rotation 781S: between +1 and 1.
Test solution: 10 mg per mL, in dehydrated alcohol.
Loss on drying 731 Dry it in vacuum at 60 for 4 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281: not more than 0.2%.
Chromatographic purity—
pH 3.5 Buffer— Dissolve 68.0 g of monobasic potassium phosphate in 1000 mL of water, and adjust with phosphoric acid to a pH of 3.5 ± 0.05.
Mobile phase— Prepare a suitable filtered and degassed mixture of water, acetonitrile, and pH 3.5 buffer (55:43:2). Make adjustments if necessary (see System Suitability under Chromatography 621).
System suitability solution— Prepare a solution in Mobile phase containing about 5 µg per mL of USP Ketoprofen RS and 1.5 µg per mL of USP Ketoprofen Related Compound D RS. [note—Protect this solution from light. ]
Standard solution— Dissolve an accurately weighed quantity of USP Ketoprofen RS quantitatively in Mobile phase to obtain a solution having a known concentration of about 0.002 mg per mL. [note—Protect this solution from light. ]
Test solution— Transfer about 100 mg of Ketoprofen, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix. [note—Protect this solution from light. ]
Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 233-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 1.6 for ketoprofen related compound D (3-acetylbenzophenone) and 1.0 for ketoprofen; the resolution, R, between ketoprofen related compound D and ketoprofen is not less than 7.0; the column efficiency, determined from the ketoprofen peak, is not less than 2250 theoretical plates; and the tailing factor for the ketoprofen peak is not more than 2.0. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 5%.
Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, run the chromatograph for seven times the retention time for ketoprofen, record the chromatograms, and measure the areas for the peaks. Calculate the percentage of each impurity by the same formula:
10,000(C / W)(ri / rS)
in which C is the concentration, in mg per mL, of USP Ketoprofen RS in the Standard solution; W is the weight, in mg, of Ketoprofen taken to prepare the Test solution; ri is the response of each individual peak, other than the main ketoprofen peak, obtained from the Test solution; and rS is the response of the main ketoprofen peak obtained from the Standard solution: not more than 0.2% of any individual impurity is found, and the sum of all impurities found is not more than 1.0%.
Assay— Dissolve about 450 mg of Ketoprofen, accurately weighed, in 25 mL of alcohol. Add 25 mL of water and several drops of phenol red TS, and titrate with 0.1 N sodium hydroxide having been standardized by a similar titration of primary standard benzoic acid. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N sodium hydroxide is equivalent to 25.43 mg of C16H14O3.
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