A community-led calibration of the Zr isotope Reference Materials: NIST RM 8299 and SRM 3169

Published

July 19, 2023

Author(s)

François L.H. Tissot, Mauricio Ibanez-Mejia, Savelas Rabb, Rebecca Kraft, Robert D. Vocke Jr., Manuela Fehr, Maria Schonbachler, Haolan Tang, Edward Young

Abstract

As the field of zirconium (Zr) stable isotopes is rapidly expanding from the study of isotope anomalies to that of mass-dependent effects, a variety of Zr standards have appeared in the literature. While each of these standards is being proposed as the ideal isotope reference material (iRM) against which all data should be reported, none of them have been shown to meet the compositional and/or conflict-of-interest-free distribution requirements put forth by the community. To remedy this situation, we here report on a community-led effort to develop and calibrate a scale defining iRM for Zr isotopes: NIST RM 8299. Developed in partnership with NIST from the widely used SRM 3169 Zr concentration standard, RM 8299 was then subjected to a thorough inter-laboratory calibration involving three laboratories. Our data show that RM 8299 meets all requirements of an ideal iRM as it is an isotopically homogeneous, high-purity standard, that is free of isotope anomalies, and whose composition is identical to that of a major geological reservoir (Mid-Ocean Ridge Basalts). Furthermore, RM 8299 is curated and distributed by NIST, a neutral, conflict-of-interest free organization, and was produced in sufficient quantities to last multiple decades. We propose that all Zr isotope data be reported against RM 8299. As SRM 3169 lots #130920 and #071226 were found to have indistinguishable composition to RM 8299, using RM 8299 as the scale defining iRM will enable direct comparison of all future data with the vast majority of the existing literature data, both for isotope anomalies and mass-dependent effects. To facilitate conversion of δ94/90Zr values reported against other Zr standards, we provide high-precision conversion factors to the RM 8299 scale obtained using the double-spike method.

Citation

Journal of Analytical Atomic Spectrometry

Pub Type

Journals

Keywords

Zr, zirconium, isotope, RM 8299, SRM 3169

Citation

Tissot, F. , Ibanez-Mejia, M. , Rabb, S. , Kraft, R. , Vocke Jr., R. , Fehr, M. , Schonbachler, M. , Tang, H. and Young, E. (2023), A community-led calibration of the Zr isotope Reference Materials: NIST RM 8299 and SRM 3169, Journal of Analytical Atomic Spectrometry (Accessed April 24, 2025)