Title: Determination of atomic
weights using new analytical techniques
Berglund, John Karl
B. Coplen, Paul
De Bièvre, John
R. De Laeter, Tiping
P. Ding, Mitsuru
Ebihara, A. M.
G. Heumann, Norman
E. Holden, Hiroshi
Hidaka, Robert D.
Loss, Kevin J.R.
Rosman, Etienne Roth,
Philip D.P. Taylor,
Ying-Kai Xiao, Shigekazu
Yoneda, and Mo-tian
New analytical techniques, including inductively coupled plasma-mass
spectrometry, have recently provided atomic weights with unparalleled
precision. The purpose of this project is to assess the uncertainties
in these new methods in atomic-weights work, evaluate published
work, and, if possible, make recommendations to update IUPAC's Table
of Standard Atomic Weights.
New analytical techniques, including inductively coupled
plasma-mass spectrometry (ICP-MS), have recently provided atomic
weights of chemical elements with unparalleled precision. For example,
ICP-MS analyses on boron reference materials distributed by the
International Atomic Energy Agency have very low uncertainties in
their atomic weights, but the values do not agree well with previous
thermal ionization mass spectrometric (TIMS) measurements. In fact,
ICP-MS values from different laboratories do not overlap even with
2-s uncertainties. The reasons for the
lack of agreement currently are not well understood. The purpose
of this project is to assess the uncertainties of these new methods
in atomic-weights work.
Meetings are planned in 2004, 2005, 2006, and 2007. Based on information
gained at the 2004 Goldschmidt Conference in Copenhagen, strategies
will be developed to allow the task group to compare uncertainties
of atomic-weight measurements made by TIMS, ICP-MS, and other methods.
In order to increase the knowledge base of the task group in ICP-MS
studies, individuals with ICP-MS experience will be identified in
Copenhagen and asked to join it.
As was learned in early August at a meeting in Ottawa, comparing
data from TIMS and ICP-MS methods is difficult. One possibility
is for task group members to develop algorithms for comparing atomic
weight uncertainties determined by TIMS, ICP-MS, and other new methods.
These algorithms will be applied to published atomic-weights literature
and the results will be presented to IUPAC's Commission on Isotopic
Abundances and Atomic Weights in Turin during the General Assembly
(2007). If the development of these new algorithms is successful,
they will provide data for the basis of a new Table of Standard
Atomic Weights, which could be submitted to PAC as a publication
titled "Atomic Weights of the Elements 2007."
Last update: 15 April 2004