COPPER SPECIATION ANALYSIS USING A CHEMICALLY-MODIFIED ELECTRODE

A carbon paste electrode modified with Amberlite IRC-718 resin, containing the chelating agent iminodiacetic acid, was used for speciation analysis. Copper was accumulated on the electrode surface when the electrode was immersed in the sample and then the amount of copper preconcentrated was evaluated by cyclic voltammetry. The chemical reaction studied is based on exchange of the iminodiacetate group attached to the electrode surface with the -competing ligand in solution. A kinetic study allowed the determination of the influence of the nature of the interfering ligand on the reaction rate. A comparison of the results obtained by this method with theoretical predictions based on thermodynamic equilibrium constants and natural ligand classification as a function of their effects is presented.