Determination of cadmium and lead in wine samples by means of dispersive liquid-liquid microextraction coupled to electrothermal atomic absorption spectrometry

Wine contains significant amounts of Cd and Pb coming from different contamination sources. The analysis of these elements still means an enormous challenge due to its low concentration levels and the complexity of the wine matrix. Therefore, new highly sensitive analytical methods are currently required. The present work reports a new method based on the use of dispersive liquid-liquid microextraction (DLLME) and electrothermal atomic absorption spectrometry (ETAAS) determination. Results demonstrate that, under optimum DLLME experimental conditions, accurate Pb determination can be easily performed using external calibration. Cadmium determination requires a standard addition calibration strategy since its accuracy is strongly affected by the presence of Zn in the wine matrix. The limits of detection afforded by the method proposed were 0.01 and 0.08 mu g L-1 for Cd and Pb, respectively. These values were around one order of magnitude lower than those previously reported for wine analysis by ETAAS. This simple methodology has been successfully employed for Cd and Pb analysis in different types of wines (i.e., white, red, rose and sparkling wines). The results are in agreement with those obtained by Inductively Coupled Plasma - Mass Spectrometry after a time-consuming microwave-assisted acid digestion treatment.