Testing miniaturized extraction chromatography protocols for combined 87Sr/86Sr and δ88/86Sr analyses of pore water by MC‐ICP‐MS

Abstract

We tested two miniaturized extraction chromatography protocols for strontium isolation based on 300 μL (Protocol 1) and 30 μL (Protocol 2) column volumes of Sr‐Spec resin, for the simultaneous determination of 87Sr/86Sr and δ88/86Sr by MC‐ICP‐MS. The accuracy and precision of the Sr isotope ratios have been evaluated by analyzing JCt‐1 and SRM 1640a reference materials, resulting in a reproducibility of 87Sr/86Sr and δ88/86Sr values of 0.000026 and 0.04‰ (Protocol 1) (2SD, n = 3), and of 0.000074 and 0.13‰ (Protocol 2) (2SD, n = 4), respectively. The Sr isotopic composition of SRM 1640a, presented here for the first time, is 87Sr/86Sr = 0.708790 ± 0.000062 and δ88/86Sr = 0.07 ± 0.10‰ (2SD, n = 6). Protocols 1 and 2 were successfully applied to pore waters extracted from marine sediment cores from the northern Barents Sea. Our results demonstrate that both protocols attain accurate 87Sr/86Sr ratios and allow the detection of natural variations in δ88/86Sr in marine pore waters. Compared to previous Sr/matrix separation methods, Protocol 2 is significantly less costly, making it particularly suitable for large‐scale oceanological and limnological studies.