The Suitability of Digestion Techniques in the Assessment of Certain Metals in Standard Reference Materials

Abstract

The assessment of various digestion methods is of utmost importance in accurately determining the concentrations of elemental metals in soil. In this study, the dry digestion method utilizing a graphite furnace oven was compared to the wet digestion method employing a microwave. Four standard reference materials, namely Randwijk clay, Hengelo sandy soil, Halle sandy soil, and Herveld clay samples, were subjected to analysis using an inductively coupled plasma optical emission spectrometer (ICP-OES). The reliability of the data obtained was ensured by calculating the recovery and error percentage of the results for both digestion methods. The findings indicate that the microwave digestion method is superior for all elements in soil samples, except for calcium (Ca), chromium (Cr), and magnesium (Mg). On the other hand, the dry digestion method may be favored for calcium (Ca), copper (Cu), chromium (Cr), magnesium (Mg), sodium (Na), nickel (Ni), and vanadium (V). A pair t-test statistical analysis was conducted to compare the two methods, revealing significant differences, except for calcium (Ca), chromium (Cr), copper (Cu), iron (Fe), potassium (K), and sodium (Na), indicating a lack of agreement between the two methods, except for these specific elements.