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 N2O 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 N2O as a reaction gas to convert Sr+ into SrO+ for in‐line separation of 87Sr from 87Rb. 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 87Sr16O/86Sr16O based on 88Sr16O/86Sr16O works to give for NIST SRM 987 a 87Sr/86Sr ratio of 0.7101 ± 0.012 (RSD = 0.17%) and for NIST SRM 1570a a 87Sr/86Sr ratio of 0.7100 ± 0.009 (RSD = 0.12%), which are within error of the accepted values. The first 87Sr/86Sr 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 precision of >99.8% can be achieved with in‐line separation of 87Sr from 87Rb at least up to solutions with 25 ppb Rb. Conclusions A minimum of 5 mg of insect tissue is required for Sr isotope analysis. This new ICP‐MS/MS method enables Sr isotope analysis in single insects, allowing population‐scale studies to be feasible and making possible applications with time‐critical uses such as biosecurity.

Abstract-The isotope fractionation of Zn in meteorites has been measured for the first time using thermal ionization mass spectrometry and a double spiking technique. The magnitude of dZn ranged from )0.29 to +0.38& amu )1 for five stone meteorites whereas the iron meteorite Canyon Diablo displays dZn of 1.11 ± 0.11& amu )1 . The results for chondrites in this work can be divided into positive and negative dZn, supporting a previous proposal that chondrites are a mixture of materials from two different temperature sources. The Zn isotope fractionation present in meteorites may represent a primordial heterogeneity formed in the early solar system. An anomalous isotopic composition of Zn obtained for the Redfields iron meteorite suggests large-scale inherited isotope heterogeneity of the protosolar nebula, or the presence of a parent body that has formed within its own isotopically anomalous reservoir. These anomalies are in the same direction but smaller than nuclear field shift effects observed in chemical exchange reactions. The isotope dilution mass spectrometry (IDMS) technique was used to measure Zn concentration, yielding a range from 20

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A thermal ionisation mass spectrometric technique enabled the abundance of Zn in geological and biological reference materials and water samples to be measured by double spiking isotope dilution mass spectrometry enriched in the 67Zn and 70Zn isotopes. In the past, thermal ionisation mass spectrometry proved to be difficult for low‐level zinc isotopic measurements. The size of Zn samples used for isotopic determination, in particular the biological RMs, represents an important breakthrough. These results represent the most accurate and precise concentrations measured for Zn in these samples. The maximum fractional uncertainty was that for TILL‐3 (2%), while the minimum fractional uncertainty was 0.7% for both BCR‐1 and W‐2. The inhomogeneity of Zn in HISS‐1 was revealed while other reference materials appeared homogeneous at the 95% confidence uncertainty. The certified concentration of Zn in HISS‐1 and IMEP‐19 by their producers are 28% and 3.8% higher than the values measured in this work. These are the first Zn concentration measurements in these materials by the isotope dilution‐TIMS technique, except for BCR‐1, NIES No 9 and IMEP‐19. Reducing the blank enabled accurate measurement in water at the ng g‐1 level demonstrating the applicability of the technique for low‐level Zn samples.