Mercury-plated thin film ITO microelectrode array for analysis of heavy metals

We have developed a mercury-plated microelectrode array based on Indium Tin Oxide (ITO) films (600 nm) prepared by rf reactive sputtering on a silicon substrate. Microelectrode behaviour of the disc arrays has been characterised by cyclic voltammetry (CV). Electroplating of mercury onto the ITO microelectrode array was carried out in a solution of Hg(NO3)2 and KNO3 by applying a potential of −1500 mV vs. Ag/AgCl/Cl− for varying charge (350-1050 μC). Mercury plating and Pb2+ pre-concentration conditions were optimised for ex situ determination of Pb2+ in aqueous solution by anodic stripping voltammetry (ASV). The sensitivity of ITO-Hg microelectrode array to Pb2+ was 130 nA(mol/l)−1.