Determination of cadmium and lead at sub-ppt level in soft drinks: An efficient combination between dispersive liquid-liquid microextraction and graphite furnace atomic absorption spectrometry

A DLLME method for extraction and preconcentration of Cd and Pb from soft drinks and further determination by GF AAS was developed. Important parameters of DLLME such as the type and volume of dispersive and extraction solvents, concentration of DDTC (complexing agent) and pH were evaluated. Better results were obtained using 500 mu L of acetone for Cd and 700 mu L of acetonitrile for Pb as dispersive solvents, 60 mu L of CCl4 as extraction solvent for both analytes and 500 mu L of 1.5% DDTC solution. Accuracy was evaluated by recovery assays and ranged from 91 to 113% for Cd and from 95 to 108% for Pb, with RSD below 10 and 7%, respectively. The LODs were 0.006 and 0.072 ng L (1) for Cd and Pb, respectively. The optimized method was applied for the determination of Cd and Pb in soft drinks with different brands and flavours. (C) 2016 Elsevier Ltd. All rights reserved.