Anodic stripping voltammetric determination of Cd and Pb with nanocarbon film electrode fabricated by unbalanced magnetron sputtering

Abstract

Nanocarbon films formed by using unbalanced magnetron sputtering equipment were employed to detect Cd and Pb using anodic stripping voltammetry. The electrode performance was evaluated in acetate and citrate buffers. The Cd-acetate complex was easily reduced because the complexation constant was moderate. This is quite different from the Cd-EDTA complex which cannot be deposited onto an electrode. In contrast, citrate buffer at lower pH is suitable for detecting Pb ion due to weak interaction between Pb2+ and citrate anion. As a result, acetate buffer (pH 5.0) and citrate buffer (pH 2.0) are the optimum solutions for determining Cd and Pb, respectively. Detection limits of 0.5 ng/mL (0.004 μmol dm-3) and 5ng/mL (0.02 μmol dm-3) were obtained for Cd and Pb ions, respectively. These detection limits are about one order of magnitude better than those obtained with a glassy carbon (GC) electrode. The morphology of the deposited Pb was studied by using Kelvin force microscopy. The deposition was more uniform on the nanocarbon film than that on the GC. These results indicate that the uniform surface of the nanocarbon film realized the homogeneous deposition of metal ions and reduced the noise level due to the small surface area.