Detection of Zinc and Lead in Wine by Potentiometric Stripping on Novel Dental Amalgam Electrodes

A simple method for detection of zinc and lead in wine by use of potentiometric stripping analyses (PSA) on the dental amalgam electrode is introduced, and demonstrated for 10 different wines, both red and white. The combination of PSA and the novel non-toxic electrode offers a fast and easy to use technique without matrix effects seen in e.g. voltammetry. Concentrations of zinc in the range of approximately 2.1*10-6 M to 11.7*10-6 M (3.5 % std. dev.) and lead in the range 9.7*10-8 M to 2.4*10-7 M (3.5 % std. dev.) were found in the actual wine samples. PSA measurements were verified against atomic adsorption spectroscopy analyses (AAS), and a good correlation factor was found (r2 = 0,96). A simple speciation study was performed by measuring the amount of zinc and lead before and after addition of acid, giving an approximately ratio between free and total amount of the metals. Estimated detection limits for zinc and lead were calculated to respectively 3.0*10-7 M and 1.5*10-8 M for 120 seconds of plating time.