Abstract
A rapid high-performance liquid chromatographic assay for the determination of the anti-inflammatory drug benoxaprofen in human plasma, is described. Plasma samples of 1.0 ml, to which benoxaprofen, and warfarin as an internal standard, had been added, were extracted with ether under acidic conditions. The samples were analyzed on a MicroPak CN-10 column using 25% acetonitrile in water (pH 2.5 with phosphoric acid). Detection was made on a variable wavelength UV absorbance detector at 309 nm.
Samples containing 0.5–10 μg benoxaprofen gave a mean extraction recovery from control plasma of 90.6 ± 6.8% (n=18). Stability tests have shown that benoxaprofen in plasma is stable for at least two weeks after freezing.