Polarographic and voltammetric determination of genotoxic substances in drinking water using mercury electrodes

Even 85 years after their introduction in analytical chemistry by Nobel Prize winner professor Jaroslav Heyrovsky, mercury electrodes are still the best available sensors for voltammetric monitoring of trace amounts of electrochemically reducible inorganic and organic substances. Their main advantages (atomically smooth surface, easily renewable surface diminishing problems with passivation so frequently encountered with solid working electrodes and large potential window in cathodic region) usually overbalance their disadvantages (very limited anodic potential window, limited mechanical stability complicating their application for measuring in flowing media and unsubstantiated fears of their toxicity). Modern variants of mercury electrodes, namely hanging mercury drop electrode, in combination with pulse techniques or accumulation of the analyte on the surface of working electrode (electrochemical or adsorptive) enable to reach micromolar or even nanomolar limits of determination for electrochemically reducible substances. Recently, increasing attention is paid to their application for the determination of trace amount of genotoxic substances in both drinking and surface waters. In this chapter, practical applications of polarographic and voltammetric methods on mercury electrodes for the determination of trace amount of various chemical carcinogens (namely nitrated polycyclic aromatic hydrocarbons, electrochemically reducible heterocyclic compounds, etc.) in drinking water will be reviewed and compared with our most recent experimental results in this field. Advantages and disadvantages of various polarographic and voltammetric methods in this field will be critically evaluated. Attention will be paid to their combination with preliminary separation and preconcentration using liquid or solid phase extraction.