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Vol. 27 No. 6
November-December 2005

IUPAC in Beijing—Division Roundups

- Division I. Physical and Biophysical Chemistry
- Division II. Inorganic Chemistry
-- Commission II.1. Isotopic Abundances and Atomic Weights
- Division IV. Polymer
- Division VIII. Chemical Nomenclature and Structure Representation
- CHEMRAWN

Division II. Inorganic Chemistry
Anthony R. West, President

Division 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.

Five 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.

With 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.”

Commission II.1. Isotopic Abundances and Atomic Weights
Michael E. Wieser, Secretary

The 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.

As 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.

The 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 project.

Differences 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.

The 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.

Authors 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 uncertainty.

The 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.

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Part 2 of the Divisions Roundups from the 2005 GA will appear in the next issue of CI (Jan.-Feb. 2006)


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