Application of a nanoporous gold electrode for the sensitive detection of copper via mercury-free anodic stripping voltammetry

摘要

This paper describes how a new mercury-free alternative electrode material, nanoporous goldn(NPG), was applied to improve the performance of detecting trace metals in stripping voltammetry.nThe NPG electrode was obtained by dealloying Zn from AuxZn1u0002x in a 40–60 mol% zinc chloride–n1-ethyl-3-methylimidazolium chloride (ZnCl2–EMIC) ionic liquid. To prevent electrode foulingnfrom surfactant adsorption, the short carbon-chain organothiol (3-mercaptopropyl)sulfonate (MPS)nwas selected to modify the NPG electrode through the formation of a self-assembled monolayern(SAM). The MPS-modified NPG (MPS@NPG) electrode not only significantly enhanced thensensitivity in detecting Cu2+ but also effectively prevented electrode surface fouling from surfactantnadsorption. The electrode is easy to prepare and can be readily renewed after each stripping experiment.nThe dynamic range of calibration curve, y ¼ 58.76x (in mA mMu00021n) + 3.90 (R2n¼ 0.999), showed verynlinear behavior with slope of 58.76 mA mMu00021n(0.1–5 mgLu00021n). The detection limit is as low as 0.002 mgLu00021n(0.031 nM). Non-ionic, anionic, and cationic surfactants were found to have no effect on Cu2+ndetection when using the MPS@NPG electrode as a sensing probe. This method was applied tondetermining the Cu2+nin a reference material and three real water samples. The results agreednsatisfactorily with the certified values.