COMPARATIVE STUDY OF FIVE DIGESTION METHODS FOR ELEMENTAL ANALYSIS OF SOIL USING ATOMIC ABSORPTION SPECTROPHOTOMETER

Journal: Acta Chemica Malaysia (ACMY)
Author: Olayinka A. Ibigbamia, Adefusisoye A. Adebawore, Samuel S. Asaolu and Samuel O. Adefemi
ISSN: 2576-6732
e-ISSN: 2576-6724

This is an open access journal distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

DOI: 10.26480/acmy.01.2025.35.43

The study evaluates the efficiency of different digestion methods for the recovery of heavy metals (Ni, Pb, Cu, Cd and Zn) from soil samples using Atomic Absorption Spectrophometry (AAS) method. Various acid mixtures including aqua regia (HCl + HNO3), aqua regia with sulfuric acid (HCl + HNO3 + H2SO4), hydrofluoric acid with perchloric acid (HF + HClO3), perchloric acid with sulfuric acid (HClO3 + H2SO4), and a combination of perchloric acid, nitric acid, and hydrofluoric acid (HClO3 + HNO3 + HF) were evaluated for effective recovery after spiking with 10, 20 and 50 ppm of studied metals. The percentage recovery of each metal were evaluated to assess the effectiveness of these digestion methods. At 10 ppm spike levels, aqua regia demonstrated high recoveries for Zn, and Cd, while HF + HClO3 showed moderate efficiency across metals. At higher spike levels (20 ppm and 50 ppm), aqua regia consistently showed high recovery rates for Zn, Cd and Pb, but moderate recoveries for Cu, and Ni. The addition of sulfuric acid to aqua regia generally reduced recovery rates slightly. HF + HClO3 and HClO3 + H2SO4 exhibited lower recoveries compared to aqua regia, indicating potential limitations in extracting metals at higher concentrations. The results suggest that aqua regia remains a robust choice for extracting a wide range of metals from soil samples, particularly at lower spike levels. However, the choice of digestion method should consider specific metal recovery requirements and the soil matrix characteristics to ensure accurate environmental and geochemical analyses.