Sphalerite and Zinc Metal Nugget Reference Materials for In Situ Zinc Isotope Ratio Determination Using fsLA‐MC‐ICP‐MS

• Published in: Geostandards and geoanalytical research 2022-09, Vol.46 (3), p.433-449
• Main Authors: Bao, Zhian, Nie, Xiaojuan, Chen, Kaiyun, Zong, Chunlei, Lv, Nan, Yuan, Honglin
• Format: Article
• Language: English
• Subjects: Ablation; Chemical composition; fsLA‐MC‐ICP‐MS; Heavy metals; homogeneity; In situ measurement; Isotopes; Lasers; Mass spectrometry; Mass spectroscopy; Measurement; NBS 123; NIST SRM 683; Reference materials; Zinc; Zinc isotopes; Zn‐rich materials
• ISSN: 1639-4488; 1751-908X
• DOI: 10.1111/ggr.12427

This study examined the micro‐homogeneity of zinc isotope composition of the NIST SRM 683 and NBS 123 reference materials using femtosecond laser ablation multi‐collector inductively coupled plasma‐mass spectrometry (fsLA‐MC‐ICP‐MS). NIST SRM 683 and NBS 123 are homogeneous in Zn isotope composition based on numerous measurements performed on twenty chips and four mounts of sphalerite using solution nebulisation (SN)‐MC‐ICP‐MS and fsLA‐MC‐ICP‐MS. The mean δ66ZnJMC‐Lyon values of NIST SRM 683 and NBS 123 determined by SN‐MC‐ICP‐MS were 0.11 ± 0.02‰ (2 standard deviation (2s), n = 100) and 0.16 ± 0.02‰ (2s, n = 62), respectively. The mean δ66ZnJMC‐Lyon values determined by fsLA‐MC‐ICP‐MS analyses for NIST SRM 683 and NBS 123 were 0.12 ± 0.05‰ (2s, n = 200) and 0.16 ± 0.05‰ (2s, n = 212), consistent with the bulk isotope compositions within uncertainty. The in situ measurement precision for NIST SRM 683 and NBS 123 was better than 0.06‰ (2s), suggesting NIST SRM 683 and NBS 123 are suitable to serve as microanalytical reference materials for Zn isotope measurement. Zinc isotopic compositions of Zn‐rich materials were also determined using fsLA‐MC‐ICP‐MS under wet/dry plasma conditions. Their δ66ZnJMC‐Lyon values were in agreement with those obtained by SN‐MC‐ICP‐MS analysis, suggesting that fsLA‐MC‐ICP‐MS is suitable to measure Zn isotopic ratios in Zn‐rich materials. Thus, this method could potentially analyse spatially resolved Zn isotope compositions at the mineral or even sub‐mineral scale, such as to address the process of ore formation or Zn redistribution in near‐surface environments. Key Points NIST SRM 683 and NBS 123 can be used as reference materials for in situ Zn isotope measurements. Recommended δ66ZnJMC‐Lyon values for NIST SRM 683 and NBS 123 are 0.11 ± 0.02‰ (2s, n = 100) and 0.16 ± 0.02‰ (2s, n = 62), respectively. δ66ZnJMC‐Lyon values of Zn‐rich minerals determined under wet plasma conditions are in good agreement with recommended values when NBS 123 served as a non‐matrix‐matched bracketing standard (calibrator).