Acidified pressurized hot water for the continuous extraction of cadmium and lead from plant materials prior to ETAAS

Acidified and pressurized hot water is proposed for the continuous leaching of Cd and Pb from plants prior to determination by electrothermal atomic absorption spectrometry. Beech leaves (a certified reference material-CRM 100-where the analytes were not certified) were used for optimizing the method by a multivariate approach. The samples (0.5 g) were subjected to dynamic extraction with water modified with 1% v/v HNO, at 250 degreesC as leachant. A kinetics study was performed in order to know the pattern of the extraction process. The method was validated with a CRM (olive leaves, 062 from the BCR) where the analytes had been certified. The agreement between the certified values and those found using the proposed method demonstrates its usefulness. The repeatability and within-laboratory reproducibility were 3.7 and 2.3% for Cd and 1.04% and 6.3% for Pb, respectively. The precision of the method, together with its efficiency, rapidity, and environmental acceptability, makes it a good alternative for the determination of trace metals in plant material. (C) 2002 Elsevier Science B.V. All rights reserved.