Application of ultrasonic to speciation analysis of heavy metals in soil

In order to reduce the operation time and improve the extraction efficiency, ultrasonic energy by means of ultrasonic bath was used to the modified Tessier sequential extraction for speciation analysis of heavy metals in soil. Extractable contents of Cu, Fe, Mn, Ni, Pb and Zn were measured by atomic absorption spectroscopy (AAS). The merit of the ultrasonic extraction (UE) applied to the modified Tessier method is not only that the operation time for the first 4 fractions was reduced from ca. 18 h to 8 h, comparing with conventional extraction (CE), but also the extraction efficiency was higher. The results for both of UE and CE were consistent. The extractable Cu, Ni and Zn in the sample No. 1 were mainly associated with the third fraction (Fe-Mn oxides fraction), and fourth fraction (organic matter fraction) in the sample No.2. The extractable Fe and Mn were all mainly associated with the third fraction, and Pb the fourth fraction in both of the samples. The effects of concentration of hydroxylamine chloride on the capability for the extraction of studied metals were also studied.