KINETICS OF DISSOCIATION OF COPPER(II)-PROLINE COMPLEX BY CYCLIC VOLTAMMETRY WITH A NAFION-COATED ELECTRODE

The kinetics of dissociation of copper(II)-proline complexes were studied by cyclic voltammetry using two types of electrode: a hanging mercury drop and a Nafion(R)-coated thin mercury film. In the former case and depending on the free ligand concentration, quasi-labile behaviour and labile behaviour were observed for identical time scales of the technique used. This was attributed to the adsorption of the negatively charged free ligand on the mercury aqueous solution interface in the potential region where Cu(II) reduction occurs, subsequently inducing the adsorption of the metal ion. The use of the Nafion-modified electrode, i.e. the latter case, seemed to avoid interferences effectively due to adsorption of negatively charged compounds. Kinetic data obtained via cyclic voltammetry are in good agreement with the literature values obtained by spectroscopic techniques.