COPPER ION-SELECTIVE ELECTRODE BASED ON A CHALCOGENIDE GLASS MEMBRANE

A chalcogenide glass membrane based on germanium-antimony-selenium and doped with 20.8% copper was used in the preparation of a copper ion-s elective electrode (ISE). It shows an almost Nernstian response of 31 mV. It is specific in the presence of Na+, K+, Ca2+, Co2+, and Ni2+ Wi th selectivity coefficients of 10(-2) for Na+ and K+, and 10(-3) for t he other ions. For both UO22+ and Zn+, the selectivity coefficient is 0.1, whereas for Al3+ and Fe3+ it is 0.06 and 0.5, respectively. Iron( II) interferes very strongly. The electrode response is independent of pH in the range 1-3. The copper ISE was used as an indicator electrod e for the potentiometric titration of copper ions in solution (10(-4)- 0.1 mol l(-1)) using standard ethylenediaminetetraacetic acid, a sharp potential change occurs at the end-point.