Determination of cephalosporins in urine and bile by capillary zone electrophoresis

A capillary zone electrophoresis (CZE) method has been developed for the determination of new cephalosporin antibiotics (cephalexin, cefadroxil, cefaclor, ceftazidim, cefsulodin, cefotaxim, cefamandol, cefuroxim, cefodizim) in urine and in bile. The determination of cephalosporins was performed as a direct method. The samples were only diluted in buffer and were injected into the apparatus without any further sample preparation. The determination and the separation of cephalosporins in both media was performed at pH 6. Urine and bile samples were analyzed using a calibration curve for cephalosporin concentrations between 10 and 500 μg/ml. The detection limit, the effective mobility and the relative standard deviation of the migration times and of the peak areas in urine and in bile were determined.