Determining copper ions in water using electrochemiluminescence

The detection of copper ions in aqueous solution using electrochemiluminescence (ECL) is reported. ECL is generated by reducing Cu2+ ions to Cu+ with hydroxylamine hydrochloride and then complexing with the chelating agent 2,9-dimethyl-1,10-phenanthroline (dmp) to form Cu(dmp)(2)(+), followed by oxidation in the presence of tri-n-propylamine (TPrA). The ECL intensity peaks a potential corresponding to oxidation of both TPrA and Cu(dmp)(2)(+), indicating that the emission is from a Cu(dmp)(2)(+) metal-to-ligand charge transfer excited state. Conditions for ECL emission were optimized and used to generate a calibration curve that was linear over the 0.1-5 mg/l (ppm) range. The theoretical limit of detection was 6 mug/l (ppb), with a practical limit of detection of 0.1 ppm. The ECL of several metal ions other than copper with dmp, and effects on Cu(dmp)(2)(+) ECL were also examined. (C) 2001 Elsevier Science BN. All rights reserved.