Anodic stripping voltammetric determination of mercury by use of a sodium montmorillonite-modified carbon-paste electrode

摘要

A sodium montmorillonite (SWy-2)-modified carbon-paste electrode has been examined for determination of trace levels of mercury. Because of its strong cation-exchange and adsorptive characteristics, SWy-2 greatly improves the sensitivity of determination of Hg~(2+). Hg~(2+) is preconcentrated and reduced on the modified electrode surface at -0.40 V and then stripped from the electrode surface during the positive potential sweep. The conditions used for determination, e.g. supporting electrolyte, pH, amount of SWy-2, accumulation potential, and accumulation time, were optimized. The peak current was linearly dependent on the concentration of mercury from 1 * 10~(-9) to 5 * 10~(-7) mol L~(-1). The detection limit (signal-to-noise ratio = 3) was 1 * 10~(-10) mol L~(-1) after accumulation for 6 min. When the SWy-2-modified carbon-paste electrode was used to detect mercury in water samples the average recovery was 101.11%.