Determination of Pb2+ in natural waters with 2-mercaptobenzimidazole-5-sulfonate (MBIS) chemically modified gold electrode.

The preparation, characterization and analytical applications of gold electrodes modified with omegamercapto alkyl/aryl sulfonates are described. The devices resulted effective for the determination of free and labile Pb(II) in water samples by anodic stripping voltammetry (Edep =−600mV) and in particular 2-mercaptobenzimidazole-5-sulfonate (MBIS) offered the best performances with detection limit of 0.4microgL−1. Quantitative stripping of Pb from the electrode surface during the anodic scan, is obtained using sodium citrate buffer (pH = 9.0) as supporting electrolyte. Natural waters were analysed by standard addition method with good recoveries (mean percentage = 97%); no fouling effects due to humic acids or other organic constituents were observed in the reported conditions.