Analysis of pirprofen in cerebrospinal fluid, plasma, and synovial fluid by high-performance liquid chromatography with electrochemical detection

We describe a high‐performance liquid chromatographic method, using electrochemical detection, for the determination of pirprofen in cerebrospinal fluid (CSF), plasma, and synovial fluid (SF). A C‐18 column with a mobile phase containing acetonitrile acetate: phosphate buffer (pH 3.0) was employed. Samples were added with phosphoric acid, then extracted into dichloromethane, evaporated, and injected into the chromatograph. A detection potential of +0.85 V was applied on the basis of current‐potential curves. Good linearity was found for each fluid in the expected range of therapeutic concentrations. The detection limit was 0.1 ng/mL for CSF, and 1 ng/mL for plasma and SF, with a recovery >96% and intraday coefficient of variation