Voltammetric determination of methylmercury and inorganic mercury with an home made gold nanoparticle electrode

This study outlines the development of a procedure for the determination of methylmercury by anodic stripping voltammetry at a gold nanoparticle-modified glassy carbon electrode (AuNPs-GCE) and for the differentiation between methylmercury and inorganic mercury. The signal of methylmercury was measured in the square wave mode using HCl as the supporting electrolyte. The procedure had good accuracy, repeatability and linearity. The determination of total mercury in solutions containing both methylmercury and inorganic mercury was performed after converting the former into the inorganic form. Different sample solution pre-treatments were tested for this purpose, and an acid digestion in a microwave oven with HNO3 and H2O2 was found to be the most effective. The selective determination of methylmercury in the presence of inorganic mercury was possible after masking the latter through reduction to the elemental state with SnCl2. The amount of inorganic mercury was determined by difference.