Correction of mass fractionation for isotope dilution analysis by MC-ICP-MS

Abstract

Isotope dilution analysis can provide precise elemental concentration and isotopic composition data in a single measurement run. However, mass fractionation correction in isotope dilution analysis can be challenging. This study presents two iterative calculation methods, based on isotopic ratios and abundances, for isotope dilution analysis of elements with at least two internal reference isotopic ratios. The strontium isotope system was used to show the details of the calculations. For convenience, a MATLAB program was created based on these calculation methods. Replicate analyses of three reference materials demonstrate that the obtained Rb and Sr concentrations and ⁸⁷Sr/⁸⁶Sr isotopic ratios are in good agreement with previously published values. In addition, two mineral Rb-Sr isochronal ages, which agree with accepted zircon U-Pb ages, demonstrate the validity of the methods presented in this study.