Dynamic approach based on iterative change of the flow direction for microwave-assisted leaching of cadmium and lead from plant prior to GF-AAS

A dynamic system for the continuous leaching of Cd and Pb from leaves based on both microwave-assistance and iterative change of the flow direction of the leachant through the extraction cell has been developed. Beech leaves (a certified reference material-CRM-where the analytes were not certified) were used for optimising the method by both univariate and multivariate approaches, depending on the interaction between variables. A slightly acid aqueous solution was used as leachant and the samples (0.5 g) were subjected to 10-15 min of 300 W microwave-assisted leaching. The target analytes were determined in the extract by graphite furnace atomic absorption spectrometry (GF-AAS). The method was validated with other CRM (Olive Leaves, 062, from the BCR) where the analytes had been certified, thus demonstrating the agreement between the certified values and those found using the proposed method. Within-and between-day reproducibility was in the range 5.3-7.7% and 4.2-4.8% for Cd and Pb, respectively.