ENHANCED AMPEROMETRIC DETECTOR FOR LOCAL-ANESTHETICS IN LIQUID-CHROMATOGRAPHY WITH METAL-OXIDE DISPERSED GLASSY-CARBON ELECTRODES

Chemically modified electrodes (CMEs) prepared by the dispersion of me tal oxide particles on a glassy carbon (GC) substrate greatly enhance the voltammetric response and amperometric detection of local anesthet ics following liquid chromatography (LC). The enhancement is more pron ounced with the GC electrodes dispersed by the metal oxides of higher oxidation states (+3, +4) and for the species exhibiting relatively sl ow electrode kinetics under given conditions. With an applied potentia l of 1.2 V (vs. SCE), LC amperometric detection of the analytes at the alpha-alumina modified GC surface gives detection limits 2-5 times lo wer than those obtained at the bare electrode. The metal oxide-dispers ed electrodes display significant improvement in sensitivity, and sele ctivity and indicate excellent preparation reproducibility and perform ance stability.