ION-EXCHANGE VOLTAMMETRY OF COPPER IONS IN CHLORIDE MEDIA AT GLASSY-CARBON ELECTRODES MODIFIED WITH POLYCATIONIC IONOMERS

Perfluorinated polycationic polymers (Tosflex) were applied for preparing polymer-modified electrodes able to preconcentrate anionic complexes of Cu+ electrogenerated in situ at the electrode/polymer interface by reducing Cu2+ solutions in the presence of chloride ions. The species incorporated into the polymeric coating, namely CuCl2-, was detected by a suitable linear sweep voltammetric reoxidation scan. The dependence of the reoxidation peak current on experimental parameters such as amount of modifier, electrogeneration-preconcentration time and solution concentrations of Cu2+ and Cl- was studied. The possibility of applying Tosflex-modified electrodes to copper speciation studies was also examined. In particular, the influence on the ion-exchange voltammetric responses of some amino acids such as histidine, glycine and glutamic acid which, at the pH employed in this study, carry positive, neutral and negative ionic charges, respectively, is discussed. Some of the advantages and limitations of Tosflex-modified electrodes compared with Nafion-coated electrodes and the hanging mercury drop electrode are critically evaluated.