METAL-DISPERSED CARBON PASTE ELECTRODES

The preparation of metal-dispersed carbon paste electrodes, based on mixing an organic binder with metalized graphite, is described. Such electrodes combine the efficient electrocatalytic activity of metal microparticles with the attractive properties of carbon paste matrices. The ability to catalyze the slow electrode reactions of hydrogen or organic peroxides, hydrazine compounds, ascorbic acid, and dihydronicotinamide adenine dinucleotide is illustrated. Carbon pastes doped with different metals (Pt, Pd, and Ru) exhibit different electrocatalytic activities, background current contributions, and hence analytical performances. Coimmobilization of an oxidase enzyme allows coupling of a biocatalytic reaction with the electrocatalytic detection of the liberated peroxide. The decrease in operating potential greatly benefits the amperometric monitoring of flowing streams. The attractive coupling of metal catalytic centers with carbon paste formulations should be very valuable for routine qualitative work.