Determination of transition metals in wine by IC, DPASV-DPCSV, and ZGFAAS coupled with UV photolysis

In the present work ion chromatography (IC), differential pulse anodic (DPASV) or cathodic stripping voltammetry (DPCSV), and Zeeman graphite furnace atomic absorption spectroscopy (ZGFAAS) were applied to the determination of heavy and transition metals in wine. The matrix is degraded by oxidative UV photolysis in a digester equipped with a high-pressure mercury lamp. The temperature of the sample is maintained at 85 +/- 5 degrees C by a combined air/water cooling system. This procedure has decisive advantages if compared with other sample pretreatment techniques. Most organic wine constituents degrade in <1 h, whereas metals quantitation remains unaffected by UV radiation, with the exception of manganese. The clear solution is directly analyzed for most common heavy and transition metals such as cadmium, cobalt, copper, iron, lead, nickel, and zinc. In the absence of standards, the results obtained by different techniques are compared and are found in good agreement. All of the considered techniques appear to be equivalent, but ZGFAAS is more time-consuming because it does not permit multielement analyses.