Project Details:

Full calibration of a new molybdenum isotopic reference material

The purpose of this project is to calibrate an internationally available certified reference material for molybdenum isotopes.  This project will, for the first time, provide the vast molybdenum isotope user community with a reliable δ-zero anchor for molybdenum isotopic data that is fully traceable to the SI norm and as such allow reliable interlaboratory comparison of Mo isotopic results.  

Over the past decade the multiple collector inductively coupled plasma mass spectrometer has enabled the determination of isotopic composition of molybdenum with unprecedented levels of precision.  Molybdenum is redoxsensitive and abundant in rocks, seawater, and an important metal in many biological processes.  Many working groups in geochemistry, the environmental and life sciences are employing isotope abundance data to investigate processes involving this element.  However, the intercomparison of results among research groups is impeded because there are no molybdenum isotopic reference materials and no agreed-upon delta zero material.  To enable interlaboratory data comparison, a commercially available material has to be calibrated and suggested as the delta zero reference material. 

The purpose of this project is to bring together key laboratories to participate in the full calibration of a suitable reference material.  In order to achieve this goal, it is necessary to first identify suitable candidates. Criteria will include a material with isotopic abundances that fall in the mid range of terrestrial isotopic composition.  The material must be distributed by recognized international organizations (i.e. IAEA, NIST, IRMM).  The material must be available in reasonable quantities and preferably in liquid form.  The calibration exercise will be carried out in three different laboratories using agreed upon analytical protocols that fulfill the requirements of the Commission on Isotopic Abundances and Atomic Weights definition of a best measurement. Finally, participants will identify and calibrate commonly used reference materials (e.g. certified seawater and USGS geochemical reference materials) to serve as secondary standards and the laboratory and represent important terrestrial molybdenum reservoirs. 

Face-to-face meetings will be organized to discuss the selection of appropriate materials, establish measurement protocols, and discuss and evaluate measurement results.  Outcomes will be disseminated as oral or poster presentations at major international conferences where significant numbers of users meet.  Data will be published in high impact peer-reviewed journals to reach as broad an audience as possible to encourage adoption of the new calibrated reference materials.

• Wieser, Michael

• Gröning, Manfred
• Meija, Juris
• Schönberg, Ronny
• Zhu, Xiangkun