The rubidium (Rb) isotope system has the potential to trace planetary evolution, magmatic‐fluid interaction and chemical weathering. These applications are based on Rb isotope measurement results with precisions fit for purpose, but measurements of low‐Rb geological materials are challenging due to large sample consumption and overload of ion‐exchange resin. Here we developed a measurement procedure for Rb isotope data (δ 87 Rb SRM984 ) of low‐Rb geological materials using MC‐ICP‐MS. Using an Aridus III desolvator and Ni standard sampler + Ni X skimmer cone combination, the Rb loading amount was reduced significantly to 20 ng. A comparison between two methods for instrumental mass‐bias correction, the sample‐standard bracketing and combined sample‐standard bracketing and internal (Zr) normalisation (C‐SSBIN), shows that C‐SSBIN could produce Rb isotope data with better intermediate measurement precisions but strictly restricted to optimal Zr/Rb ratio. The robustness of this method was demonstrated by monitoring δ 87 Rb SRM984 data of two in‐house Rb isotope standards, replicates, some reference materials with δ 87 Rb SRM984 values previously reported, and element‐doped and matrix‐spiked synthetic solutions. Based on repeated measurements of Rb isotope standards and reference materials, the long‐term (over one year) intermediate precision was better than 0.05‰ (2 s , standard deviations). We additionally recommend thirteen reliable reference materials for future Rb isotope ratio measurements.

Ya‐Qi Zhang

Wei Wei

Zhuoying Zhang

Xia Hu

Hui‐Min Yu

Fang Huang

Geostandards and Geoanalytical Research

GEOSTANDARDS & GEOANALYTICAL RESEARCH 是一本国际期刊，致力于推进与地质和环境样品的化学分析相关的参考材料、分析技术和数据质量的科学。论文在同行评审后被接受发表。

Geostandards and Geoanalytical Research is an international journal dedicated to advancing the science of reference materials, analytical techniques, and data quality related to the chemical analysis of geological and environmental samples. All papers are accepted for publication after peer review.

《Geostandards and Geoanalytical Research》是一本国际期刊，专注于推动与地质和环境样品的化学分析相关的参考材料、分析技术和数据质量的科学研究。所有论文均经过同行评审后接受发表。

Category	Quartile
地球科学	2
地球科学, 地球化学与地球物理	2

Rubidium Isotope Measurements of Low‐Rb Geological Materials by MC‐ICP‐MS

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Journal Info

Category	Quartile
GEOCHEMISTRY & GEOPHYSICS	2