Comparison of digestion methods for total content of microelements in soil samples by HG-AAS

摘要

Several digestion methods including the reverse of aqua regia and different combinations of concentrated acids (HCl, HNO;) were compared. Three acid digestion procedures were applied to certified samples to offer a proper method for determination of Zn, Cu, and Ni in soil samples. Two low pressure microwave heating programmes modified (nitric acid and Ultrapure water; nitric acid with clorhydric acid) and one procedure without pressure microwave (nitric acid with clorhydric acid and hydrogen peroxide) were tested in this study by using one standard reference material (Estuarine Sediment-1646) and ten soil samples. Short digestion time, less acid consumption, and high extraction efficiency were noted as the advantages of microwave digestion procedures. The concentration of three heavy metals (Zn, Cu, Ni) in soil samples was measured in three sampling sites of Romania, South- Eastern Romanian Plain, Central and Southern Dobrogea. The concentration of heavy metals was measured by using the atomic absorption spectrometry method and these concentration values were situated in normal limits for these chemical elements. In conclusion, to determine the total contents of heavy metals in soil samples studied, in principle any method of digestion carried out in a microwave oven can be used.