A Series of Fe(‐Ti) Oxide Reference Materials for In Situ Fe Isotope Measurement

Iron isotope ratios of Fe(‐Ti) oxide minerals have been widely used in constraining different geological processes. Laser ablation‐MC‐ICP‐MS has been commonly used to identify subtle Fe isotopic variations of these iron oxides, but matrix‐matched reference materials for calibration are still lacking. Here, five mineral pellets were prepared using a high‐temperature and high‐pressure sintering method. These pellets are proved to be homogenous in Fe isotope ratio by femtosecond LA‐MC‐ICP‐MS. The reference values (δ 56 Fe IRMM‐014 ) determined by solution nebulisation MC‐ICP‐MS are 0.08 ± 0.03‰, 0.29 ± 0.02‰, 0.20 ± 0.06‰, 0.23 ± 0.03‰ and 0.32 ± 0.01‰ for MtFe‐2 (magnetite), HemFe‐1 (haematite), IlmFe‐1 (ilmenite), VTiMtFe‐1 (V‐Ti magnetite) and VTiMtFe‐2 (V‐Ti magnetite), respectively. Previous magnetite reference material MtFe‐1 can be used as the bracketing calibrator for MtFe‐2 and HemFe‐1. Similarly, there is no matrix effect between MtFe‐2 and HemFe‐1. IlmFe‐1 can be used as the bracketing calibrator for VTiMtFe‐1 and VTiMtFe‐2. VTiMtFe‐1 and VTiMtFe‐2 can be used as the bracketing calibrator for each other. The effects of blank on the determination of Fe isotopes are negligible. The analysis of natural magnetite and ilmenite validates their practical use in geological studies. The prepared reference materials are in sufficient quantities to be shared with other laboratories.