Sammendrag
The importance of monitoring the content of heavy metals in wines and spirits at trace levels is obvious and several analytical methods are obvious. Being in situ methods, voltammetric and potentiometric stripping methods are very attractive, but the toxicity of mercury makes limitations in particular for use in the field. We have introduced a non-toxic electrode material similar to dental amalgam for use in voltammetry. Its electrochemical properties are similar to a silver electrode. However, it possesses high hydrogen overvoltage and this enables one to detect metals like zinc, nickel and cobalt. Recently we have also reported that other silver alloys with a few percent of mercury, lead, bismuth etc. also can be used as electrode material. As such solid electrodes are found to give stable results over several weeks, without any maintenance, and because this method greatly facilitates monitoring of heavy metals, attempts to apply such methods are carries out. The present presentation deals with the practical applications for heavy metal determinations in ppb levels in wines and spirits. It is possible to measure zinc, cadmium, lead and other metals in red and white wines, as well as in brandies with minor treatment of the natural samples, and this can be adapted to continuous monitoring. Possible matrix effects are also studied by adapting the method of �medium exchange�. We have previously found that audible sound may greatly increase the voltammetric signal using liquid mercury as well as silver as electrode material. This is also applied on the actual systems, and potentiometric stripping will be evaluated. Finally, some of our analytical forensic data from a criminal case in Norway with thallium in brandy is presented, with results being close to AAS measurements. It was found that the electrode could be used repeatedly for all the measurements, without any fouling.
Vis fullstendig beskrivelse
