Copper ion-selective electrode based on a chalcogenide glass membrane

Abstract

A chalcogenide glass membrane based on germanium–antimony–selenium and doped with 20.8% copper was used in the preparation of a copper ion-selective electrode (ISE). It shows an almost Nernstian response of 31 mV. It is specific in the presence of Na⁺, K⁺, Ca²⁺, Co²⁺, and Ni²⁺ with selectivity coefficients of 10^–2 for Na⁺ and K⁺, and 10^–3 for the other ions. For both UO₂²⁺ and Zn²⁺, 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 electrode 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.