Determination of Trace Mercury in Saltwaters at Screen-Printed Electrodes Modified with Sumichelate Q10R

Abstract

The results of a study on the determination of trace levels of mercury in natural saltwaters using screen-printed carbon electrodes modified with Sumichelate Q10R, a chelating resin containing dithiocarbamate groups, which binds mercury strongly and selectively are reported. Cyclic voltammetric measurements indicate that mercury(II) is preconcentrated by complexation at the modified electrode, giving peak currents which are about one order of magnitude higher than those obtained at an unmodifed screen-printed electrode. The voltammetric pattern is characterized by a broad reduction peak to which a sharp and well-resolved reoxidation peak is associated. Trace (subnanomolar) concentrations of mercury can be determined at the screen-printed modified electrode by adopting a complexation-anodic stripping procedure with detection via differential pulse voltammetry. The method is characterized by a low detection limit (3σ blank/sensitivity) of 12 pM with 20 min complexation and 5 min reduction at –0.5 V. Excess copper interferes in the analysis of mercury only when present in more than hundred-fold excess. Data concerning the application of modified screen-printed electrodes to the analysis of mercury in water samples from the channels of Venice (Italy) are presented and discussed.