27 No. 6
in Beijing—Division Roundups
Division I. Physical and Biophysical
- Division II. Inorganic Chemistry
-- Commission II.1. Isotopic Abundances and Atomic Weights
- Division IV. Polymer
- Division VIII. Chemical
Nomenclature and Structure Representation
II. Inorganic Chemistry
Anthony R. West, President
II reported it had a successful two-day meeting in which members
were optimistic about the future and determined to put behind
them a tumultuous period in which the division had “bottomed
out.” Average attendance at the meetings was 16, with
several young observers who stayed throughout and contributed
significantly to the discussions.
new project proposals were discussed; two are ready for submission
and should effectively use up the remainder of the division
allocation for this biennium. Three more need working up,
two in molecules and one in materials, for the next biennium.
One of the molecules projects may become a joint project with
the Committee on Chemistry Education. Several of the young
observers (Russia, UK, USA) are keen to become involved with
this project. A sixth project proposal is being presented
by a former young observer, now the German national representative,
to the interdivisional subcommittee on materials chemistry.
This is likely to become a cross-division project on terminology
in nanomaterials and nanotechnology and may still be submitted
within this biennium.
elections taking place in September 2005 for four titular
members, the division is poised to move in new directions.
During his presentation to the Council, Division President
Tony West exclaimed, “We are just scratching the surface
of materials chemistry. IUPAC can do much more.”
II.1. Isotopic Abundances and Atomic Weights
Michael E. Wieser, Secretary
Commission on Isotopic Abundances and Atomic Weights met for
two days of evaluations and discussions under the chairmanship
of Prof. Tiping Ding. As well as the normal scientific work
of the commission, considerable discussion also took place
on ways to make the information produced by the commission
of greater value to the wider chemical and scientific community.
presented in detail in the Wire
section (in print on page 18), the standard atomic weights
of 16 chemical elements have been revised based on new determinations
of isotopic abundances and reviews of previous isotopic abundances
and atomic masses.
Subcommittee on Isotopic Abundance Measurements (SIAM) evaluated
published isotope abundance data in order to determine the
“best measurements.” This task has become increasingly
important with the emergence of new analytical techniques
that enable the analyst to produce isotope-amount ratio measurements
to very high precision. The challenge is to ensure that the
uncertainty calculations that lead to the standard atomic
weights are consistent. Therefore, members of the isotopic
composition of selected elements project are developing systematic
and comprehensive evaluation criteria to account for systematic
uncertainties during sample preparation and measurement. SIAM
also recognizes that the user community is in need of isotopic
composition data. In response, project members are developing
a database that presents the evaluated isotopic compositions,
range of variation of isotopic composition, and the atomic
weight as decided by the commission. These evaluation tools
are of immediate use to SIAM and will be a fundamental component
of its work as the subcommittee incorporates the outcomes
of the report on the isotopic compositions of the elements
in measured isotope-amount ratios of stable carbon isotopes
(13C/12C), commonly called delta carbon-13
values, are used to understand processes in oceanography,
atmospheric sciences, biology, paleoclimatology, geology,
environmental sciences, and food and drug authentication.
Progress in these fields requires smaller measurement uncertainties
to be achieved. Advances in instrumentation enable increasingly
precise measurements. Nevertheless, laboratories measuring
the same specimen often disagree by 10 times their reported
“uncertainty” of measurement.
commission recommends that delta carbon-13 values of all carbon-bearing
materials be measured and expressed relative to the VPDB on
a scale normalized by assigning values of -46.6 parts per
thousand relative to L-SVEC lithium carbonate and +1.95 parts
per thousand relative to NBS 19 calcium carbonate, and authors
should clearly state so in their reports.
are encouraged to report their delta measurement results for
the carbon-13 values of NBS 22 oil, USGS41 L-glutamic acid,
IAEA CH 6 sucrose, or other internationally distributed reference
materials, as appropriate for the measurement method concerned.
Adoption of these guidelines should enable laboratories worldwide
that are measuring the same sample to report delta carbon-13
values that agree with one another to within the measurement
commission also formally recognized the significant contributions
made by past commission members Dr. Steffen Peiser and Dr.
John Gramlich, who both passed away in the past year.
2 of the Divisions Roundups from the 2005 GA will appear
in the next issue of CI (Jan.-Feb. 2006)
last modified 28 October 2005.
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