This article reports on the results of the comparative analysis covering the interrelation between the surface morphology of thick-®lm graphite electrodes (TFGE's), which were modi®ed 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 ®lms 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 ®lms on electrochemical properties of MTFGE's has been discussed. Formation of an intermediate layer with anomalous electrochemical behavior was observed using only electrodes modi®ed with mercury in situ from the solution. Electrodes modi®ed 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.

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SH-and SS-groups content and their ratio is one of the most important factors of organism antioxidant system. Change in ratio of thiols to disulfides can serve as an indicator of oxidative stress. Anodic stripping voltammetry and anodic stripping voltammetric titration (direct and reverse variants) methods are proposed for determination of thiols and disulfides concentration. Disulfides are preliminary reduced with sodium sulfite.reaction is used to provide the information. Unreacted silver ions concentration is determined by anodic stripping voltammetry method using platinum working electrode. Calibration free method is suggested. The possibilities of express analysis of blood and its fractions are described. Reliability of results and accuracy are confirmed by model solutions analysis and recovery study of whole blood and its fractions. Results of whole blood, erythrocyte mass, plasma and serum taken from different groups of patients investigations are given, that demonstrate perspectives of the application methods in clinical practice.

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