| Abstract: | ABSTRACT Liquid mercury and liquid diluted mercury amalgams have been superior as electrode material for the use of voltammetry for analytical purposes. This is mainly due to the high overvoltage to hydrogen, which enables one to use a wide potential range for the measurements. Due to the toxicity of mercury and liquid diluted mercury compounds, the use of such compounds are increasingly restricted, and cannot be included in voltammetric devices for field and online applications. The present authors have studied the properties of dental amalgam and related solid amalgams as electrode material in voltammetry. Due to the special properties of dental amalgam compared with mercury itself it is not toxic. It has been found that dental amalgam and related solid amalgams have a very high overpotential to hydrogen, allowing one to carry out trace analyses at potentials sufficiently negative to allow determination of e.g. zinc, cobalt, nickel and iron at trace levels. This have previously been difficult except when using a mercury or a mercury film electrode. The present preliminary paper describes such electrodes and some practical applications for trace heavy metal analyses, using differential pulse stripping voltammetry. Such determinations are very important for field and online analyses of pollutants in soil and groundwater, and the electrode can be used repeatedly. Further improvements can obviously be obtained by optimising the composition of the alloy. |
