PEROXIDASE-MODIFIED AND TETRACYANOQUINODIMETHANE-MODIFIED GRAPHITE PASTE ELECTRODE FOR THE MEASUREMENT OF GLUCOSE-LACTATE GLUTAMATE USING ENZYME-PACKED BED REACTOR

A flow injection analysis sensor for the measurement of glucose/lactat e/glutamate is reported. The glucose oxidase/glutamate oxidase/lactate oxidase was immobilized on silanized controlled pore glass particles and packed into a Teflon column (i.d., 1.2 mm; length, 40 mm) to give a bed for glucose/lactate/glutamate. The hydrogen peroxide formed by t he enzymatic reaction in the packed bed was monitored by a horseradish peroxidase- and tetracyanoquinodimethane (TCNQ)- modified graphite pa ste electrode at 50 mV vs Ag/AgCl. The glucose oxidase/lactate oxidase /glutamate oxidase were regenerated in the packed bed, whereas peroxid ase was regenerated in the TCNQ-mediated graphite paste electrode by t he oxidation of TCNQ. The oxidized TCNQ was electrochemically reduced at 50 mV vs Ag/AgCl. The cathodic current obtained by the reduction of TCNQ determined the concentration of the injected analytes in the pac ked bed. The system showed very rapid response. Response curves for th e analysis of peroxide, glucose, lactate, and glutamate are reported. (C) 1995 Academic Press, Inc.