Determination of Radiogenic Sr-87/Sr-86 and Stable delta Sr-88/86(SRM987) Isotope Values of Thirteen Mineral, Vegetal and Animal Reference Materials by DS-TIMS

摘要

This work presents new Sr-87/Sr-86 and delta Sr-88/86(SRM987) isotopic values of thirteen mineral, vegetal and animal reference materials. Except for UB-N, all our results are consistent with previously published data. Our results highlight intermediate precisions among the best presently published and a non-significant systematic shift with the calculated delta Sr-88/86(SRM987) mean values for the three most analysed reference materials in the literature (i.e., IAPSO, BCR-2 and JCp-1). By comparison with the literature and between two distinct digestions, a significant bias of delta Sr-88/86(SRM987) values was highlighted for two reference materials (UB-N and GS-N). It has also been shown that digestion protocols (nitric and multi-acid) have a moderate impact on the delta Sr-88/86(SRM987) isotopic values for the Jls-1 reference materials suggesting that a nitric acid digestion of carbonate can be used without significant bias from partial digestion of non-carbonate impurities. Different delta Sr-88/86(SRM987) values were measured after two independent Sr/matrix separations, according to the same protocol, for a fat-rich organic reference material (BCR-380R) and have been related to a potential post-digestion heterogeneity. Finally, the delta Sr-88/86(SRM987) value differences measured between animal-vegetal and between coral-seawater reference materials agree with the previously published results, highlighting an Sr isotopic fractionation along the trophic chain and during carbonate precipitation.