Accuracy Evaluation of Ultrasound Probe Sonication and Microwave-Assisted Extraction Systems for Rapid Single Extraction of Metals in Soils

摘要

The accumulation of metals in soils and sediments causes a potential risk to human health due to the transfer of these elements to other environmental compartments. However, metals are present in soils under different chemical forms or types of binding, so the total metal content is a poor indicator of their bioavailability, mobility or toxicity, since these properties basically depend on the chemical association of the different soil components. Therefore, the environmental impact of metalliferous soils is better assessed on the basis of the environmental accessibility of metals, i.e. the bioavailable forms for plants. In the present work, ultrasonic probe sonication (UPS) and microwave-assisted extraction (MAE) have been evaluated as alternatives to the conventional Standards, Measurements and Testing program (SM&T) procedures for single extraction of metals in soils, in order to reduce the extraction time and the consumption of samples and extracting agents. Optimization studies were carried out on the certified reference materials (CRMs) BCR 483 (Sewage sludge amended soil) and BCR 700 (Organic rich soil) for accuracy evaluation of the proposed methods. Extractable concentrations of Cd, Cr, Cu, Ni and Zn using 0.01 M calcium chloride (in BCR 483), and also of Pb with 0.43 M acetic acid and 0.05 M ethylenediaminetetraacetic acid at pH 7.0 (in both CRMs) were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).