Issue 9, 2022

High-precision iron isotopic measurements in low resolution using collision cell (CC)-MC-ICP-MS

Abstract

Here we present an analytical method for Fe isotopic measurements in low resolution mode, using a Nu Sapphire collision cell-equipped multi-collector inductively coupled plasma mass spectrometer by standard-sample bracketing. High Fe sensitivity was obtained through reducing Ar based interference by over 9 orders of magnitude whilst other analytes remained unaffected. The effects of Fe concentration, Fe beam intensity and HNO3 molarity mismatch between the standard and sample and the presence of matrix elements have been evaluated. The long-term analyses of JMC Fe and BCR-2 indicate that the obtained isotopic ratios are highly reproducible, with precisions of better than ±0.03‰ for δ56Fe (2SD). Such accurate and precise data could be acquired via 3 to 6 repeat measurements consuming 50–100 ng Fe, which has improved by a factor 40 compared to those previously reported on other instruments. Accurate measurements were achieved by closely matching Fe intensities between the sample and standard (a 5% mismatch would create a 0.02‰ offset in the 56Fe/54Fe ratio). On the other hand, the ratio of the concentration between the matrix elements and Fe, such as CNa/CFe, CMg/CFe, CCa/CFe, CTi/CFe and CNi/CFe, should be kept under 0.1, CK/CFe under 0.3, CAl/CFe and CCu/CFe under 1, and CCo/CFe and CZn/CFe under 2 to avoid any matrix effect. In addition, high precision Fe isotopic data were obtained on twenty-one geological reference materials and were highly consistent with the literature values. Furthermore, we obtained δ56Fe of standard chalcopyrite (XTC) for the first time: 0.127 ± 0.027‰ (2SD, n = 3).

Graphical abstract: High-precision iron isotopic measurements in low resolution using collision cell (CC)-MC-ICP-MS

Supplementary files

Article information

Article type
Paper
Submitted
10 mar 2022
Accepted
28 júl 2022
First published
30 júl 2022

J. Anal. At. Spectrom., 2022,37, 1869-1875

High-precision iron isotopic measurements in low resolution using collision cell (CC)-MC-ICP-MS

J. Wang, D. Tang, B. Su, Q. Yuan, W. Li, B. Gao, K. Chen, Z. Bao and Y. Zhao, J. Anal. At. Spectrom., 2022, 37, 1869 DOI: 10.1039/D2JA00084A

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