Project Details:
Evaluation of Radiogenic Abundance Variations in Selected Elements
| Project No.: | 2009-023-1-200 |
| Start date: | 2009-09-01 |
| End date: | 0000-00-00 |
| Division: | Inorganic Chemistry Division |
The purpose of this project is to evaluate isotopic abundance variations in selected elements, including Re, Os, Rb, Sr, K, Nd, Sm, Hf, Lu, and Ar in a range of materials, based on peer-reviewed measurements, to create graphical plots of these data, and to provide CIAAW with information to update the Table of Standard Atomic Weights.
Recent developments in inorganic mass spectrometry enable isotope ratio measurement of radiogenic elements at unprecedented precision. A steadily growing body of measurements shows radiogenic isotope abundance variations for elements such as Re, Os, Rb, Sr, K, Nd, Sm, Hf, Lu, and Ar. This raises the question of how far current IUPAC recommendations for the standard atomic weights of these elements and their respective uncertainties incorporate any natural variations in isotope abundances.
In July 2009 and in July 2011, task group members will convene prior to the IUPAC general Assemblies to evaluate published information. Particular attention will be paid to possible sources of systematic bias in the measurement uncertainty, the selection of materials for analysis, and the variability of measured isotope ratios in these materials. Graphical plots of these data with atomic weight axes, delta scale axes, and mole fraction axes, presented for various types of chemicals and substances, in a manner similar to previous SNIF diagrams.
Recommendations will be incorporated into those generated by the Subcommittee on Isotope Abundance Measurements (SIAM) and they will be sent to CIAAW for approval. Approved changes will be incorporated into the next CIAAW Table of Isotopic Composition of the Elements (TICE) and Table of Standard Atomic Weights (TSAW).
The technical report will complement the earlier IUPAC (SNIF) report “Isotope-Abundance Variations of selected elements“ (Pure Appl. Chem. 74:1987–2017, 2002) in which these chemical elements could not be comprehensively covered because of lack of manpower.