The effect of sample preparation on metal determination in soil by FAAS

Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated. Different procedures for total dissolution of soil: I - HF+HClO4, H3BO3, HCl digestion (conventional heating), II - HF+HClO4, H3BO3 digestion followed by fusion with LiBO2 (conventional heating) and III - HF+HCl+HNO3, H3BO3 digestion (microwave heating), as well as a leaching procedure with HNO3+HClO4, HCL were tested and compared. For quality assessment, the certified reference material S-l soil was used. For most of the investigated metals, the best accuracy and precision were achieved when the procedure I or LII were used. The developed procedure was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions.