Project Details Evaluated Published Isotope Ratio Data (2011-2013)

Project No.:
Start Date:
01 January 2012
End Date:
30 June 2016


Evaluate isotope ratio publications between 2011 and early 2013 to determine “best isotope ratio measurements” for compilation and publication in a 2013 TICE (Table of Isotopic Compositions of the Elements), recommend “new” standard atomic-weight values, and publish “Atomic Weights of the Elements 2013” in Pure Applied Chemistry, which will also include a table of relative atomic masses.


The aim of this project is to evaluate new isotope ratio publications between 2011 and early 2013. The evaluated data will be incorporated into the CIAAW Table of Standard Atomic Weights.

The SIAM (Subcommittee for Isotopic Abundance Measurements) in CIAAW recognizes that there are a number of elements that need particular attention and for which significant publications are expected as an outcome of this project.

In August 2013, task group members will convene in Istanbul, prior to the IUPAC General Assembly, to evaluate recently published isotope ratios and resulting atomic-weights reports in a face-to-face meeting. Detailed discussions and calculations will be carried out on any chemical element for which new isotope ratio information exists. Particular attention will be paid to authors’ evaluations of uncertainty, the selection of materials for analysis, and the variability of isotope ratio measurements in these materials. In a second 2-day meeting in August 2013, task group members will present their recommendations for adoption of best isotopic composition ratios and new standard atomic weights to the Commission on Isotopic Abundances and Atomic Weights at the General Assembly in Istanbul. It is anticipated that new standard atomic weights will be recommended. Subsequently, a publication titled “Atomic Weights of the Elements 2013” will be prepared for Pure and Applied Chemistry. An additional publication in J. Phys. Chem. Ref. Data is anticipated. Note, lead will not be considered in this project because it is the subject of a separate project proposal because of complications in the lead isotope system.


Aug 2013 – The Subcommittee on Isotopic Abundance Measurements (SIAM) met in Gebze, Turkey, on August 4-5, and evaluated published isotope ratio data. SIAM made the recommendations to the CIAAW, which were accepted during the 2013 CIAAW meeting. The IUPAC Table of Isotopic Composition of the Elements 2013 will be published in Pure and Applied Chemistry.

Sep 2013 – Release regarding the revisions of the Standard Atomic Weights (posted 23 Sep 2013)

July 2014 – Production of TICE-2013 is well-underway and the project is expected to be completed shortly.

Aug 2015 – Release regarding the Standard Atomic Weight of Ytterbium (posted 24 Aug 2015)

Jan 2016 – In an article titled ‘Weighty decisions‘, published online in Chemistry World on 22 January 2016, Juris Meija (CIAAW chair) explains why we need to revise atomic weights.

The following two reports have been recently approved and are in production in PAC 2016:

  • Atomic weights of the elements 2013 (IUPAC Technical Report), DOI 10.1515/pac-2015-0305; PAC 2016, Volume 88, Issue 3, Pages 265–291
  • Isotopic compositions of the elements 2013 (IUPAC Technical Report), DOI 10.1515/pac-2015-0503PAC 2016, Volume 88, Issue 3, Pages 293–306

Page last updated: 12 July 2016