title: Evaluation of capillary zone electrophoresis and micellar electrokinetic capillary chromatography with direct injection of plasma for the determination of cefotaxime and its metabolite.
abstract: Quantitative aspects of capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC) were investigated for the determination of cefotaxime (C) and its deacetyl metabolite (DA) in human plasma in a concentration range of therapeutic interest. For CZE, plasma samples spiked with C and DA were injected after deproteinization with acetonitrile, and analytes were separated in a fused silica capillary using a borate buffer at pH 9.2 as electrolyte; no suitable internal standard was found. For MECC, plasma samples spiked with C, DA, and theobromine as internal standard were directly injected after dilution with water and analyzed using a phosphate buffer, pH 8.00, containing 165 mM SDS as separation electrolyte and a fused silica capillary. Both methods gave satisfactory interday precision with respect to migration times (RSD < 1%) and gave linear responses over the concentration ranges investigated (5-100 mg L-1 C and 5-20 mg L-1 DA). For CZE, intraday RSD (n = 4 graphs) between the slopes of the calibration graphs was acceptable (5.7%) for C. The corresponding figures for interday precision (n = 4 days) were fair (16.1%) in comparison to those obtained with MECC, for which the RSD was 1.49% when theobromine was used as internal standard. A satisfactory interday precision between slopes was also obtained with MECC even without the use of an internal standard (RSD = 4.38%), which demonstrated the ruggedness of this method. Detection limits (S/N = 3) were about 2 mg L-1 (CZE) and 1 mg L-1 in plasma (MECC) for C and DA. MECC was shown to be superior with regard to simplicity, rapidity, precision, and sensitivity.
authors.affiliation: Laboratoire de Chimie Analytique, Faculté de Pharmacie, Université Montpellier I. France.
authors.forename: G
authors.initials: G
authors.lastname: Castaneda Penalvo
authors.forename: M
authors.initials: M
authors.lastname: Kelly
authors.forename: H
authors.initials: H
authors.lastname: Maillols
authors.forename: H
authors.initials: H
authors.lastname: Fabre
mesh_terms: D002439:Cefotaxime / Q000031:analogs & derivatives / Q000032:analysis / Q000097:blood*; D002845:Chromatography; D019075:Electrophoresis, Capillary / Q000379:methods*; D006801:Humans; D008823:Micelles
chemical_list: D008823:Micelles; C029281:desacetylcefotaxime; D002439:Cefotaxime