Evaluation of microwave-assisted digestion methods for ID-ICP-MS characterization of KRISS lake sediment CRM 109-05-002

Abstract

Accurate elemental analysis of sediment samples is crucial for effective environmental monitoring, with certified reference materials (CRMs) serving as key tools for method validation of analysis procedures. Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) is widely recognized for its high reliability and is commonly employed in CRM development; however, its application to environmental samples is often limited by challenges in developing effective digestion methods. In this study, four optimized microwave-assisted acid digestion methods using combinations of HNO₃, HF, HCl, H₃BO₃, and HBF₄ were systematically compared for the ID-ICP-MS analysis of a newly produced lake sediment CRM (KRISS CRM 109-05-002) for 14 elements: Fe, Mg, Ti, Ca, Ba, Zn, Cr, Ni, Pb, Cu, Sn, Sb, Cd, and Se. The robustness and broad applicability of these digestion methods were further verified using NIST estuarine sediment SRM 1646a and NMIJ lake sediment CRM 7303-a. It is shown that although all four digestion protocols produced consistent results for most elements, special consideration is required for elements that are sensitive to fluoride precipitation or that require fluoride for stabilization. Element-specific digestion methods were then selected to characterize and to evaluate the homogeneity and stability of the KRISS sediment CRM. This study provides a practical framework for applying ID-ICP-MS to sediment CRMs and highlights the potential of HBF₄ as a viable alternative to HF in multi-elemental sediment analysis.