SIMULTANEOUS DETERMINATION OF CEFOXITIN, CEFUROXIME, CEPHALEXIN AND CEPHALORIDINE IN PLASMA USING HPLC AND A COLUMN-SWITCHING TECHNIQUE

A new high performance liquid chromatographic method was developed using a column-switching technique for the simultaneous determination of cephalexin, cefuroxime, cefoxitin and cephaloridine in plasma. The plasma samples were injected onto a precolumn packed with Corasil RP C18 (37-50 μm) after simple dilution with an internal standard solution in 0.01 M acetate buffer (pH 3.5). Polar plasma components were washed out using 0.01 M acetate buffer (pH 3.5). After valve switching, the concentrated drugs were desorbed in back-flush mode and separated on a Partisil ODS-3 column using acetonitrile in 0.02 M acetate buffer (pH 4.3) (15:85, v/v) as the mobile phase. The method showed excellent precision with good sensitivity and speed with a detection limit of 0.5 μg/ml. The total analysis time per sample was less than 25 min, and the mean coefficients of variation for intra- and inter-assay were both less than 4.9 %. This method has been successfully applied to plasma from rats after subcutaneous injection of cefuroxime. © 1990 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH.