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

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 O as a reaction gas for accurately determining Sr isotopes in insects with Sr < 100 ng.