Direct determination of Cd, Cu and Pb in wines and grape juices by thermospray flame furnace atomic absorption spectrometry

Abstract

The applicability of thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was evaluated for direct determination of Cu, Cd and Pb in wines and grape juices. The developed procedure does not require preliminary acid digestion of the samples. The optimum conditions for determination of Cu, Cd and Pb in wines were studied and the performance was compared to those typically obtained by flame atomic absorption spectrometry (FAAS). A sample volume of 150 μL was introduced into a heated nickel tube at a flow rate of 0.54 mL min −1 and 0.14 mol L −1 HNO 3 was used as sample carrier flowing at 2.5 mL min −1 for determining all analytes. The effect of ethanol concentrations on Cu, Cd and Pb absorbance signals were studied. All determinations were carried out by adopting optimized conditions and quantification was based on the standard additions method. Limits of detection (LOD) of 12.9, 1.8 and 5.3 μg L −1 ( n = 14) for Cu, Cd and Pb, respectively, were obtained for wine samples (3 σ blank/slope, n = 14). Relative standard deviations (R.S.D., %) of 2.7, 2.1 and 2.6 for Cu, Cd and Pb, were obtained ( n = 6) for wine samples. The values determined for grape juice samples were similar to these ones. The analytical throughput was 45 determinations h −1 and accuracy was checked by addition-recovery experiments.