Yanli Liu, Kun Guo
We investigated and compared three Sr purification techniques using AG50W-X12, Sr-spec and DGA resins prior to determining radiogenic Sr isotopic ratios by TIMS and MC-ICP-MS. Three chromatographic separation protocols were performed on eighteen geological reference materials, including twelve igneous rocks, four sedimentary rocks, and two marine sediments. Notably, we investigated the applicability of DGA resin for Sr purification in geological materials of diverse composition and determined key parameters related to sample loading capacity. Sr-spec and DGA resins are superior in terms of elution efficiency and Sr recovery compared with AG50W-X12. Sr-spec resin enables the simultaneous separation of Sr, Ba and Pb, and DGA resin allows the one-step separation of Sr and Ca. For samples with high HREE contents, Sr-spec and DGA resins are both suitable for Sr purification. The obtained 87Sr/86Sr ratios of the Chinese reference materials are in good agreement with published values, indicating the homogeneity of 87Sr/86Sr isotope ratios of these reference materials (supplied by the National Certified Reference Materials Resource Center) and their strong potential for usage as alternatives to USGS and GSJ reference materials. Furthermore, the Sr isotopic composition of SBC-1 is reported as 0.724154 ± 0.000032 (2SD).