Analytica Chimica Acta 458 (2002) 249–256 Voltammetry using a dental amalgam electrode for heavy metal monitoring of wines and spirits Øyvind Mikkelsen, Knut H. Schrøder ∗ Department of Chemistry, Norwegian University of Science and Technology, N-7491 Trondheim, Norway Received 20 June 2001; received in revised form 30 November 2001; accepted 11 December 2001 Abstract We have introduced a non-toxic electrode material similar to dental amalgam for use in voltammetry. Its electrochemical properties are like a silver electrode. However, it possesses a higher overvoltage towards hydrogen than silver, and therefore enables detection of metals like zinc, nickel and cobalt. 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 to various samples have been are carried out. The present paper deals with the determination of zinc and lead at nanogram per milliliter levels in wines and spirits with only minor treatment of the samples. The procedure may easily be adapted to continuous monitoring. 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 to the actual systems. Finally, model determinations of thallium in brandy with the dental amalgam electrode are compared with atomic absorption spectrometric (AAS) measurements. It was found that the electrode could be used repeatedly, without fouling, and with results close to those found by the AAS method. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Voltammetry; Dental amalgam electrode; Wine; Online; Medium exchange; Zinc; Cadmium; Thallium; Lead 1. Introduction Voltammetric methods are very attractive for deter- mining heavy metals at trace levels. Pure liquid mercury or liquid mercury amalgams are superior as electrode materials in voltammetry for analytical purposes [1–3]. This is mainly due to the high over- voltage for hydrogen, which renders possible a wide working potential range for the electrode. There has, however, been a growing concern about the general use of mercury because of its toxicity. This includes the use of pure mercury as an electrode material in ∗ Corresponding author. Tel.: +47-73596205. E-mail address: knut.schroder@chem.ntnu.no (K.H. Schrøder). voltammetry. Even for laboratory use, restrictions are expected to appear in the future. Therefore, it is of great interest to find new alternative electrode materials for use in voltammetry. Numerous papers have been published dealing with alternative electrodes, but all these electrodes have limited analytical value because they cannot operate at potentials more negative than -900 mV due to their low hydrogen overpotential. This is a great drawback since important metals like zinc, nickel and cobalt have half-wave potentials at more negative values, and therefore cannot be detected by the use of these electrodes. However, some interesting results using mercury-free film electrodes have been reported [4–7], 0003-2670/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0003-2670(01)01606-3