Use of ultrasonic energy for shortening the sequential extraction of metals from river sediments

Ultrasonic energy delivered by means of a probe was used to reduce the operation time in each of the stages corresponding to the Tessier sequential extraction procedure when it was applied to metal fractionation in a river sediment. The optimum extraction conditions (amplitude and sonication time) were specifically selected in each step for Cu, Cr, Ni, Pb and Zn. Extractable metal contents obtained in each stage by both the conventional and ultrasonic extraction procedures were measured by Flame-Atomic Absorption Spectrometry and the results were statistically compared (P = 0.95). Although significant differences were found for Cu in the three first stages and for Pb and Zn in the two last stages, the total extractable metal contents obtained for these elements were similar when using both methods. Ni was always quantitatively extracted and Cr was almost not leached using the proposed accelerated extraction scheme.