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Vol.
28 No. 2
March-April 2006
Calibration of Organic and Inorganic Oxygen-Bearing
Isotopic Reference Materials
During the past three decades, the determination of the relative
amounts of stable isotopes of the light elements (H, C, N,
O, and S) has dramatically increased because of expanded use
in hydrology, environmental studies, microbiology, forensic
investigations, atmospheric investigations, oceanography,
and other fields. In the past 10 years, the determination
of the relative amounts of the isotopes of oxygen in organic
and inorganic solids has increased because of developments
in instrumentation. In the past 5 years, several new oxygen
isotopic reference materials have been prepared. However,
the values of the relative amounts of oxygen isotopes in these
new materials, and in older materials, are not well known.
Thus, the problem arises that two isotope laboratories analyzing
the same sample may not report the same result within analytical
uncertainty, because they do not know what values to accept
for internationally distributed oxygen isotopic reference
materials.
The purpose of this two-year project is to bring together
expert analytical laboratories (Jena, Reston, Leipzig, Canberra,
and Zurich) to measure the relative amounts of oxygen isotopes
in isotopic reference materials. This highly coordinated analytical
effort will include inorganic materials, organic materials,
atmospheric oxygen, and two water reference materials.
Strict analytical protocols will be designed and followed
by all laboratories. An initial phase of the project will
be to assess the oxygen exchangeability of potential materials
to eliminate those with exchangeable oxygen. At the conclusion
of the analytical effort, task group members will convene
for a three-day workshop to determine consensus values and
uncertainties. Isotopic reference materials considered for
this project include: IAEA-CH-3 cellulose, IAEA-CH-6 sucrose,
IAEA-600 caffeine, IAEA-601 & IAEA-602 benzoic acid, USGS40
& USGS41 L-glutamic acids, USGS32 KNO3, IAEA-NO-3
KNO3, USGS34 KNO3, USGS35 NaNO3,
NBS-127 BaSO4, IAEA-SO-5 BaSO4, IAEA-SO-6
BaSO4, and methionine.
For more information and comments, contact the task group chairman, Tyler B. Coplen <[email protected]>.
www.iupac.org/projects/2005/2005-022-1-200.html
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last modified 10 August 2006.
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