Speeding up HCL extractions by employing ultrasound energy to evaluate trace elements bioavailability in sediments

Abstract

A three factors analysis of variance was used to test the significance of the type of vessel, the type of material and the number of replicates in the preparation of sediment samples using an ultrasonic bath. The conventional extraction with HCl 1.0 mol L-1, for 0.5, 4 and 12 h, has been modified, applying an ultrasonic bath, in order to speeding up the sample preparation time. Trace metals were measured by an ICP OES. The best results were obtained using a Teflon® vessel with a flat bottom. For all metals but Ni it was demonstrated the feasibility of working in triplicates in the ultrasonic bath, without compromising the efficiency and/or the precision of the extraction. Leaching efficiency enhanced with increasing sonication time from 1 to 50 min. For most elements the ultrasound-assisted leaching could reduce the conventional extraction time from 12 h to 50 min or even less (i.e. 6 min for Pb). The precision obtained was comparable to values obtained for the conventional acid extraction. The proposed method is a fast, inexpensive and easy alternative for screening of the potential mobility and bioavailability of metals in sediments. © 2009 Sociedade Brasileira de Química.