IMPROVED SOLID-PHASE EXTRACTION PROCEDURE FOR ASSAY OF CEPHALOSPORINSIN HUMAN URINE SAMPLES

Solid phase extraction technique has been evaluated for the treatment of urine samples in the analysis of cephalosporins before injection in to an HP-Hypersil ODS-C-18 column. Cephalexin, cefotaxime, cefazolin, cefuroxime, and cefoxitin were tested with seven different reversed-ph ase extraction column cartridges and the obtained urine extracts were not clean. However, 3M Empore ex-traction disk cartridges packed with octadecyl (C-18) bonded silica provided clean extracts with a single e xtraction. The recoveries of the five cephalosporins ranged from 56 to 60 % in the 1.25- 500 mu g/mL concentration range. The assay was accu rate, precise, and adequate for testing the drug content in urine samp les. The detection limit found for the five drugs was 0.25 mu g/mL. af ter an injection of 10 mu L. The reliability of this study was tested bq analyzing a urine sample containing cefuroxime after a minimum sing le dose administration (250 mg).