Accumulation voltammetry of copper(II) using a carbon paste electrode modified with di-8-quinolyl disulphide

Abstract

The accumulation voltammetry of copper(II) was investigated with a carbon paste electrode modified with di-8-quinolyl disulphide (DQDS). The DQDS was reduced to quinoline-8-thiol by applying a suitable potential. Copper(II) was accumulated on the electrode as the copper(II)-quinoline-8-thiol complex at a constant potential in 0.1 mol dm^–3 acetate buffer. The reduction peak of the copper(II) complex was then observed at –0.30 V by scanning the potential in a negative direction using the differential-pulse mode. The calibration graph for copper(II) was linear over the range 3 × 10^–9–2 × 10^–6 mol dm^–3 with accumulation for 5 min at –0.05 V. As copper(II) was selectively accumulated on the electrode, the influence of concomitant ions was negligible. The method was applied to the determination of copper(II) in Geological Survey of Japan rock reference materials.