title: Pre-column switching techniques for the determination of drugs and metabolites in body fluids in research and routine analysis.
abstract: The use of a column switching system for direct injection of samples and of a sample clean-up on reversed phase pre-columns is described. The pre-columns were filled with spherical C-18 silica gel of particle size 30 microns. Two applications are reported on: (1) the direct injection of serum samples for the simultaneous analysis of nine antiepileptic drugs and metabolites and (2) the determination of phenytoin and of carbamazepine in serum ultra-filtrates. The purge liquid for the sample clean-up was diluted phosphoric acid, and the eluent mixture for the chromatographic separation was water/acetonitrile. The analytical column (length 12.5 cm) was filled with C-18 silica gel of particle size 5 micron. A gradient elution was chosen for the first application, while the second application was carried out using isocratic chromatographic conditions.
mesh_terms: D000818:Animals; D001800:Blood Specimen Collection; D001826:Body Fluids / Q000032:analysis; D002220:Carbamazepine / Q000097:blood; D002417:Cattle; D002498:Centrifugation; D002852:Chromatography, Ion Exchange; D006801:Humans; D004364:Pharmaceutical Preparations / Q000032:analysis*; D010672:Phenytoin / Q000097:blood; D012710:Serum Albumin, Bovine / Q000032:analysis; D014462:Ultrafiltration
chemical_list: D004364:Pharmaceutical Preparations; D012710:Serum Albumin, Bovine; D002220:Carbamazepine; D010672:Phenytoin