Analysing Sr isotopes in low‐Sr samples such as single insects with inductively coupled plasma tandem mass spectrometry using N 2 O as a reaction gas for in‐line Rb separation

作者：David T. Murphy, Charlotte M. Allen, Osama Ghidan, Genevieve Dickson, Wan‐Ping Hu, Ethan Briggs, Peter Holder, Karen Armstrong · 发表于：Rapid Communications in Mass Spectrometry · 年份：2019 · DOI：10.1002/rcm.8604 · 被引用次数：21 · 研究领域：Isotope Analysis in Ecology、Aquatic Invertebrate Ecology and Behavior、Animal Ecology and Behavior Studies

Rationale Strontium isotopes are valuable markers of provenance in a range of disciplines. Limited amounts of Sr in low‐mass samples such as insects mean that conventional Sr isotope analysis precludes their use for geographic origins in many ecological studies or in applications such as biosecurity. Here we test the viability of using inductively coupled plasma tandem mass spectrometry (ICP‐MS/MS) with N 2 O as a reaction gas for accurately determining Sr isotopes in insects with Sr < 100 ng. Methods Strontium isotopes were determined in solution mode using ICP‐MS/MS with 0.14 L/min N 2 O as a reaction gas to convert Sr + into SrO + for in‐line separation of 87 Sr from 87 Rb. The Sr isotope reference standards NIST SRM 987, NIST SRM 1570a and NIST SRM 1547 were used to assess accuracy and reproducibility. Ten insect species collected from the wild as a proof‐of‐principle application were analysed for Sr concentration and Sr isotopes. Results Using ICP‐MS/MS we show for the first time that internal mass bias correction of 87 Sr 16 O/ 86 Sr 16 O based on 88 Sr 16 O/ 86 Sr 16 O works to give for NIST SRM 987 a 87 Sr/ 86 Sr ratio of 0.7101 ± 0.012 (RSD = 0.17%) and for NIST SRM 1570a a 87 Sr/ 86 Sr ratio of 0.7100 ± 0.009 (RSD = 0.12%), which are within error of the accepted values. The first 87 Sr/ 86 Sr ratio of NIST SRM 1547 is 0.7596 ± 0.0014. Strontium analyses were run on 0.8 mL of 0.25–0.5 ppb Sr, which equates to 2–4 ng of Sr. Strontium isotope analysis with a precisi...