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P. Galler, A. Limbeck, S. Boulyga, G. Stingeder, T. Hirata, T. Prohaska:
"Development of an On-line Flow Injection (FI) Sr/Matrix Separation Method for Accurate, High Throughput Determination of Sr Isotope Ratios by Multi Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS)";
Analytical Chemistry, 79 (2007), 5023 - 5029.

This work introduces a newly developed on-line flow injection (FI) Sr/Rb separation method as an alternative to the common, manual Sr/matrix batch separation procedure, since total analysis time is often limited by sample preparation despite the fast rate of data acquisition possible by inductively coupled plasma-mass spectrometers (ICPMS). Separation columns containing ~100 µL of Sr-specific resin were used for on-line FI Sr/matrix separation with subsequent determination of 87Sr/86Sr isotope ratios by multiple collector ICPMS. The occurrence of memory effects exhibited by the Sr-specific resin, a major restriction to the repetitive use of this costly material, could successfully be overcome. The method was fully validated by means of certified reference materials. A set of two biological and six geological Sr- and Rb bearing samples was successfully characterized for its 87Sr/86Sr isotope ratios with precisions of 0.01-0.04%. Based on our measurements we suggest 87Sr/86Sr isotope ratios of 0.71315+/-0.00016 (2 SD) and 0.70931+/-0.00006 (2 SD) for the NIST SRM 1400 bone ash and the NIST SRM 1486 bone meal, respectively. Measured 87Sr/86Sr isotope ratios for five basalt samples are in excellent agreement with published data with deviations from the published value ranging from 0 to 0.03%. A mica sample with a Rb/Sr ratio of ~1 was successfully characterized for its 87Sr/86Sr isotope signature to be 0.71824+/-0.00029 (2 SD) by the proposed method. Synthetic samples with Rb/Sr ratios of up to 10/1 could successfully be measured without significant interferences on mass 87, which would otherwise bias the accuracy and uncertainty of the obtained data.

isotope ratios, flow-injection, ICP-MS