Mg Isotope Interlaboratory Comparison of Reference Materials from Earth-Surface Low-Temperature Environments

To enable quality control of measurement procedures for determinations of Mg isotope amount ratios, expressed as δ26Mg and δ25Mg values, in Earth-surface studies, the δ26Mg and δ25Mg values of eight reference materials (RMs) were determined by inter-laboratory comparison between five laboratories and considering published data, if available. These matrix RMs, including river water SLRS-5, spring water NIST SRM 1640a, Dead Sea brine DSW-1, dolomites JDo-1 and CRM 512, limestone CRM 513, soil NIST SRM 2709a and vegetation NIST SRM 1515 apple leaves, are representative for a wide range of Earth-surface materials from low-temperature environments. The inter-laboratory variability, 2s (twice the standard deviation), of all eight RMs ranges from 0.05 to 0.17‰ in δ26Mg. Thus, it is suggested that all these materials are suitable for validation of δ26Mg and δ25Mg determinations of Earth-surface geochemical studies