Sammendrag
A new �green� electrode material similar to dental amalgam has been introduced for use in voltammetry. Its electrochemical properties are similar to a silver electrode, but possesses high hydrogen overvoltage to detect metals like zinc, nickel and cobalt. In voltammetry, dental amalgam has some major advantage compared with mer-cury as electrode material. Firstly, it substitutes the use of toxic mercury with a material being used by billions of people even in the mouth, an d further billions buried without any increase of mercury in the soil surrounding the cemeteries, this being of particular impor-tance for online monitoring in field. Secondly, the electrode may be used over several weeks without any maintenance, someth ing that is essential for online monitoring. Thirdly, the use of a solid electrode simplifies the construction of the voltammetric cell. The stability over time and reproducibility for voltammetric analyses using the dental amalgam electrode have be en evaluated. Zinc, cadmium, and lead may be detected directly in the sample by the dental amalgam electrode when a proper supporting electrolyte is added. We have previously found that audible sound may greatly increase the voltammetric signal u sing liquid mercury and silver as electrode material. Similar enhancement is valid using dental amalgam electrodes, then squeezing the detection limit down to the ppb level and even lower, without any need for stirring and bubbling with nitro-gen gas du ring the process. This is very promising to be used for remote online monitoring of heavy metals in soil and waters, where no alternative methods are available, except from using voltammetry with the mercury electrodes, the latter being environmentally unaccept-able at least for field use. Recently we have reported that other silver alloys with a few percent of mercury, lead, bis-muth etc. also can be used as electrode material. This is further investigated in our labo-ratories, with advantages as well as disadvantages compared with the use of dental amalgam as electrodes.
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