Modified thick-film graphite electrodes: Morphology and stripping voltammetry

This article reports on the results of the comparative analysis covering the interrelation between the surface morphology of thick-film graphite electrodes (TFGE's), which were modified with mercury by reduction of mercury (II) ions from solutions (in situ) and solid compounds preliminary immobilized on the working surface of the electrodes (MTFGE's), and electrochemical and analytical characteristics of both analyte elements (Cu, Pb, Cd) and mercury. Conditions of the formation and destruction of films of insoluble mercury compounds have been examined both during electrochemical regeneration of the electrode surface and during deposition of the mercury coating. The effect of these films on electrochemical properties of MTFGE's has been discussed. Formation of an intermediate layer with anomalous electrochemical behavior was observed using only electrodes modified with mercury in situ from thr solution. Electrodes modified preliminary with an insoluble mercury compound are free from this drawback. The methods of voltammetry and microscopy in situ (in real time) have been used.