Determination of Lead in Croatian Wines by Graphite Furnace Atomic Absorption Spectrometry

A method has been developed for direct determination of lead in wine by graphite furnace atomic absorption spectrometry (GFAAS) with Zeeman-effect background correction. The thermal behaviour of Pb during pyrolysis and atomisation stages was investigated without matrix modifier and in the presence of Pd(NO₃)₂, Pd(NO₃)₂ + Mg(NO₃)₂ × 6H₂O, and NH₄H₂PO₄ + Mg(NO₃)₂ × 6H₂O as matrix modifiers. A simple 1:1 dilution of wine samples with Pd(NO₃)₂ as a matrix modifier proved optimal for accurate determination of Pb in wine. Mean recoveries were 106 % for red and 114 % for white wine, and the detection limit was 3 μg L^-1. Within-run precision of measurements for red and white wine was 2.1 % and 1.8 %, respectively. The proposed method was applied for analysis of 23 Croatian wines. Median Pb concentrations were 33 μg L^-1, range (16 to 49) μg L^-1 in commercially available wines and 46 μg L^-1, range (14 to 559) μg L^-1 in home-made wines. There were no statistically significant differences (P<0.05) in Pb concentration between commercial and home-made wines or between red and white wines.