Measurement of plasma ketoprofen by a rapid high-performance liquid chromatography assay

The authors developed a high performance liquid chromatography assay for the determination of plasma ketoprofen concentration using a single-step extraction, a short chromatographic separation of 3 min, and a sample volume of 50 microliters. The assay possessed linearity up to 500 mg/l, sensitivity down to at least 1 mg/l, average recovery of 100.1%, and run-to-run precision (n = 20) of 4.6% at a level of 10 mg/l and 2.2% at a level of 40 mg/l. Furthermore, the assay was free of interference from 51 prescription and over-the-counter medications. The authors conclude that the method described here is ideally suited for the determination of ketoprofen concentration in a clinical laboratory setting for the purpose of therapeutic monitoring and assessment of toxicity.