CHEMICALLY-MODIFIED MICROELECTRODES FOR CAPILLARY ELECTROPHORESIS ELECTROCHEMISTRY

In this paper, we report the design and application of two chemically modified microelectrodes for capillary electrophoresis. The electrodes are based on the immobilization of two different types of modifiers into a carbon paste matrix. The first design incorporated the electrocatalyst cobalt phthalocyanine, which was used to catalyze the oxidation of several analytes including the thiols cysteine and glutathione. These thiols could be detected to levels of 3.1 X 10(-8) and 3.0 x 10(-7) M, respectively. This electrode was also employed for the analysis of cysteine in urine, illustrating the increase in selectivity for these types of electrodes. The second design consisted of immobilized glucose oxidase and was employed for the selective detection of glucose. These modified carbon paste microelectrodes were found to be very stable and reproducible when used as detectors for capillary electrophoresis.