Enhancement effect of iodide ion on differential pulse anodic stripping voltammetry of copper

Abstract

The peak of copper by differential pulse anodic stripping voltammetry was enhanced by the addition of iodide ion. Copper was deposited on the hanging mercury drop electrode (HMDE) for 5 min at -0.5 V vs. SCE and stripped in 0.1 mol dm-3 acetate buffer solution (pH 4.5) containing 2.5 × 10-5 mol dm-3 iodide ion. The peak current increased about 4 times as large as that in the solution without iodide ion. The stripping peak current was largely influenced by the scan rate. The maximum peak current was observed at 2 mV s-1, and when the scan rate became faster than 2 mV s-1, the peak current decreased. The peak current was proportional to the concentration of copper over the range of (5 × 10-8 ~ 7×10-7) mol dm-3. The relative standard deviation for 5 runs at 1 × 10-7 mol dm-3 Cu (II) was ca. 3 % and the lower detection limit was 0.2 ppb under the deposition time of 10 min. This method also facilitated the determination of copper in the presence of chloride ion. When copper was stripped in the solution containing 1 × 10-2 mol dm-3 chloride ion, the peak of copper was obscured and the relation between the peak current and the concentration of copper became non-linear. But by the addition of iodide ion the peak current was increased, and the linearity was restored. The effects of other co-existing ions were studied. © 1980, The Japan Society for Analytical Chemistry. All rights reserved.