Analytical Method for Comparison of Suitable Wet Digestion Methods for Heavy Metal Analysis in Soil around a Cement Industry

The approach of determination of precision and use of statistical analysis was applied in order to determine the suitable acid mixture for digestion of soil sample for heavy metal analysis in this work. Four different acid mixtures (HNO3 (60%v/v), HNO3:H2SO4 (2:9), HNO3/HCl (1:3), HNO3/HCl/H2SO4 (5:1:1), were compared over nine selected heavy metals (Pb, Cr, Cd, Ni, Zn, Fe, Mn, Co and Cu), and soil near a cement factory were analyzed . The precision for each of the metal in each of the acid mixture, the recovery and analysis of variance were applied to determined the most suitable acid mixture for digestion. From the results it was deduced that the t-calculated for 6 metals (Cd (0.577), Co (1.165), Mn (0.380), Cu (0.545), Ni (1.449) and Zn (1.424) (Cd, Co, Mn, Ni, Cu and Zn) were not significantly different for methods HCl:HNO3 (3:1) and HNO3:HCl:H2SO4 (5:1:1), except for Fe, Cr and Pb with significant difference. he heavy metal precision results, shows that method HNO3:HCl:H2SO4 (5:1:1) , had 7 metals with higher precisions which includes Fe and Cr, while HCl:HNO3 (3:1) had 5 metals with higher precision but does not include Fe and Cr. The statistical analysis revealed that method HNO3:HCl:H2SO4 (5:1:1) was the most efficient digestion method for the soil heavy metal analysis as it had given a significant high recovery (p