Voltammetric behaviour and trace determination of copper at a mercury-free screen-printed carbon electrode

Screen-printed carbon electrodes (SPCEs), without chemical modification, have been investigated as disposable sensors for the measurement of trace levels of Cu2+. Cyclic voltammetry was employed to elucidate the electrochemical behaviour of Cu2+ at these electrodes in a variety of supporting electrolytes. For all of the electrolytes studied the anodic peaks, obtained on the reverse scans, showed that the Cu2+ had been deposited as a thin layer on the surface of the SPCE. The anodic peak of greatest magnitude was obtained in 0.1 M malonic acid. The possibility of determining Cu2+ at trace levels using this medium was examined by differential pulse anodic stripping voltammetry (DPASV). The effect of Bi3+, Cd2+, Fe3+, Hg22+, Pb2+, Sb3+ and Zn2+ on the Cu stripping peak was examined and under the conditions employed, only Hg22+ was found to significantly effect the response gained. The sensors were evaluated by carrying out Cu2+ determinations on spiked and unspiked serum and water samples. The mean recovery was found in all cases to be >90% and the performance characteristics indicated the method holds promise for trace Cu2+ levels by employment of Hg-free SPCEs using DPASV.