Development and validation of extraction methods for determination of zinc and arsenic speciation in soils using focused ultrasound Application to heavy metal study in mud and soils

To evaluate metal availability in soils many extraction procedures exist which can be divided in two groups: sequential extraction and simple extraction. Both extraction procedures are time consuming, because they need long mechanical shacking time. Nowadays, ultrasonic extraction is merging as an alternative to develop more rapid methods. Methods have been optimised and validated for replacing extraction with mechanical shaking by sonication in order to simplify analytical procedures, which is highly necessary when many samples have to be tested. Zinc and arsenic have been selected for developing total and sequential extraction procedures. Chemical species of arsenic have been determined. These methods have been successfully applied to the determination of heavy metal content in fractions and soluble metal in mud coming from Aznalc?llar spill, soils contaminated with them and control soils to evaluate the degree of contamination and bio-availability of different metals.