STUDY OF LABILITY OF HEAVY-METALS IN WINES WITH DIFFERENT DEGREES OF AGING THROUGH DIFFERENTIAL-PULSE ANODIC-STRIPPING VOLTAMMETRY

DPASV is a precise, highly sensitive, low-cost analytical technique which allows for the determination of total content of trace metals and at the same time provides information on the stability of metal-ligand unions. In this study, the content of Zn, Cd, Pb, and Cu in three wines with different aging periods subjected to three different treatments (digestion, acidification to pH 1, and dilution) was studied to determine total metal concentration and distinguish the labile fraction from that displaceable by acids. Previously, the influence of deposition time and sample volume on potential and intensity of each metal was studied. Zn is the cation with the greatest total content and lability. Pb is complexed to the natural pH of wine but is easily displaceable at pH 1. Cu forms very strong unions at pH 1, and stability is even greater if the wine is young and organic matter is not very oxidized. Concentration of Cd is approximately 1 mu g/L.