COMPARISON OF MICROWAVE AND CONVENTIONAL EXTRACTION TECHNIQUES FOR THE DETERMINATION OF METALS IN SOIL, SEDIMENT AND SLUDGE SAMPLES BY ATOMIC SPECTROMETRY

A description is given of an extraction method for the determination of metals in sediment and soil samples using aqua regia [HCl-HNO3 (3 + 1)] and a microwave oven. The elements Cd, Cr, Cu, Fe, Mn, Pb and Zn were measured in the solutions by means of atomic absorption spectrometry (flame or electrothermal) and inductively coupled plasma atomic emission spectrometry. The results for the analysis of six reference materials after microwave aqua regia extraction showed close agreement with the stated values. A comparison between microwave extraction and conventional reflux extraction for 30 samples showed that the former method gives the same or slightly higher results for the seven elements tested in sediments, soil and suspended matter.