APPLICATION OF A CHELITE-P MODIFIED CARBON-PASTE ELECTRODE TO COPPER ANALYSIS AND SPECIATION

A carbon paste electrode modified with the commercial resin Chelite P, containing amino-phosphonic groups, was used in the determination and speciation of copper. Copper analysis was performed with cyclic volta mmetry and differential pulse voltammetry, allowing copper determinati on in the mu g/L level. A detection limit of 1.9 mu g/L (3 sigma) was found for a 10 min preconcentration. Interferences from other ions and organic substances were examined. For speciation purposes, a ligand c ompetition methodology was used and different model ligands in solutio n were tested. Copper complexes were characterized as a function of th eir thermodynamic and kinetics properties. Results were compared with those obtained employing a strong chelating resin (containing iminodia cetic acid) as electrode modifier. The method was applied to a water s ample from the Jarama river in Madrid, where copper was mainly present as strong low-dissociating complexes.