Zeolite-modified electrodes with analytical applications
Zeolite-modified electrodes (ZMEs) have been widely investigated because of their chemical, physical, and structural characteristics (shape, size, and charge selectivities; physical and chemical stabilities; high ion-exchange capacity; hydrophilic character; etc.), which make them of high interest in the design of electroanalytical systems. The paper presents recent literature data about fundamental and practical aspects related to the obtaining and applications of ZMEs. Some new ZMEs based on carbon paste incorporating soluble pheno-thiazinic dyes adsorbed on X-type zeolites are assessed comparatively, and the influence of some experimental parameters on the electrochemical response of these electrodes was investigated. The kinetic parameters for the heterogeneous electron-transfer process corresponding to the surface-immobilized mediators were determined, and all observed differences were used as evidence of the influence of the mediator structure and of the zeolite nature on the electrochemical activity of the new electrodes and on their electrocatalytic properties toward β-nicotinamide adenine dinucleotide (NADH) or ascorbic acid (AA) electro-oxidation and H2O2 electroreduction.