FORMATION OF A MERCURY PLATED CARBON-PASTE ELECTRODE BY ELECTRO REDUCTION OF A MERCURY(II) DIETHYLDITHIOCARBAMATE MODIFIED CARBON-PASTE

A novel approach to formation of a mercury film electrode (MFE) at the surface of a carbon paste electrode is proposed in this paper. This M FE is easy to fabricate, has good reproducibility and avoids the use o f a plating mercury solution. In this new type of MFE, mercuric diethy ldithiocarbamate (Hg(DDTC)(2)) was mixed with graphite powder and para ffin oil to form a chemically modified carbon paste electrode. When a -0.95V potential was applied to the electrode, the Hg(II) (in Hg(DDTC) 2) was reduced to metallic Hg, thus forming a mercury film at the surf ace of the carbon paste electrode. The characteristics of this MFE wer e studied. This modified electrode was used in anodic stripping voltam metry. Conditions for the simultaneous determination of trace amount o f Pb(II) and Cd(II) were also investigated.