Determination of trace mercury in saltwaters at screen-printed electrodes modified with sumichelate Q10R

The results of a study on the determination of trace levels of mercury in n atural saltwaters using screen-printed carbon electrodes modified with Sumi chelate Q10R, a chelating resin containing dithiocarbamate groups, which bi nds mercury strongly and selectively are reported. Cyclic voltammetric meas urements indicate that mercury(II) is preconcentrated by complexation at th e modified electrode, giving peak currents which are about one order of mag nitude higher than those obtained at an unmodifed screen-printed electrode. The voltammetric pattern is characterized by a broad reduction peak to whi ch a sharp and well-resolved reoxidation peak is associated. Trace (subnano molar) concentrations of mercury can be determined at the screen-printed mo dified electrode by adopting a complexation-anodic stripping procedure with detection via differential pulse voltammetry. The method is characterized by a low detection limit (3 sigma blank/sensitivity) of 12 pM with 20 min c omplexation 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. Dat a concerning the application of modified screen-printed electrodes to the a nalysis of mercury in water samples from the channels of Venice (Italy) are presented and discussed.