||I U P A C
Organizations & People
Isotope ratio measurements by mass spectrometric techniques are
required in basic and applied research e.g. geology, environmental
sciences, biomedicine and human nutrition research. The advent of
new mass spectrometric techniques, the improvement of existing techniques
and the broadening of applications have result in a tremendous increase
in reported data over recent years. As no guidelines exist to date
on how to perform high quality isotope ratio measurements, the evaluation
of published data becomes increasingly difficult. This project will
define recommendations to improve the quality and comparability of
isotope ratio measurements. Because of the diversity of available
techniques, instrumentation and element specific characteristics this
project will be limited to the definition of generally applicable
guidelines. Sources of bias in sample preparation, ion generation,
ion separation and ion detection will be outlined. Protocols for bias
control for the most commonly used techniques in isotope ratio mass
spectrometry, i.e. thermal ionization mass spectrometry (TIMS), inductively
coupled plasma mass spectrometry (ICPMS) and gas isotope ratio mass
spectrometry (GIRMS), will be defined. As a consequence, evaluation
of published data will be facilitated.
June 2004 update - Recent activities indicate that even
a basic consensus amongst the different user groups is difficult to
achieve. Quality control issues, especially in the field of multicollector
inductively coupled plasma mass spectrometry (MC-ICP-MS), are subject
to often emotional discussions. Based on these observations it has
been decided to move away from a publication of guidelines to a publication
that discusses the various sources of systematic bias in isotope ratio
measurements and the various strategies how to control underlying
effects. By creating the awareness for these effects and providing
a choice of practical approaches for their control, quality standards
in isotopic analysis are expected to be further improved, which is
the final aim of the project.
> Publication of a paper on perspectives of inorganic mass spectrometry
Walczyk T (2004) TIMS versus multicollector ICP-MS: coexistence or
struggle for survival? Anal. Bioanal. Chem. 378, 229-231 [doi:
June 2005 update - Over the past two years it became clear
that it is not possible to come-up with a consensus within the community
as the basis for the acceptance of generally applicable guidelines.
However, the primary reasoning for the Commission of Isotopic Abundances
and Atomic Weights (CIAAW) to pursue on this project was to facilitate
evaluation of published isotope ratio measurements by CIAAW in the
future. Through these evaluations, CIAAW identifies if currently valid
recommendations for the Standard Atomic Weight of the elements and
their natural isotopic abundances need to be modified. Essentially,
either an incomplete consideration of systematic sources of bias or
the lack of sufficient details in the publication makes it often difficult
to assess their impact on measurement accuracy in practice. For this
reason it is proposed to modify the title as well as the intended
primary outcome of the project from "Guidelines for mass spectrometric
isotope ratio measurements" to "Guidelines for reporting
mass spectrometric isotope ratio measurements".
Jan 2007 update - A draft of the document will be submitted
to PAC within the next 12 months for publication.
Jan 2008 - A draft titled 'Explanatory Glossary of Terms Used
in Expression of Relative Isotope Ratios and Gas Ratios' is submitted
to public review comments until 31 May 2008 > see
Last Update: 24 January 2008
you want to update this information, contact us by e-mail
Do not forget to include the Project Number,
your name and relation with that project
Page last modified 24 January 2008.
Copyright ©1997-2008 International Union of Pure and Applied Chemistry.
Questions or comments about IUPAC, please contact, the Secretariat.
Questions regarding the website, please contact web