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Isotopic measurements can give insight in processes in the environment as well as in living organisms. For example, isotopes can be used for tracking the circulation of water, provenance of an agricultural product or assessing anthropogenic contributions to greenhouse gases.
The research at IRMM focuses on isotopic measurements:
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of nitrogen, boron and strontium in water, or carbon and lead on particulate matter in air;
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of compound specific isotope analysis of polycyclic aromatic hydrocarbons (PAH) on particulate matter in air;
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to assess the compliance to bio-agriculture farming practices by measuring nitrogen and strontium isotopic composition in foodstuffs.
Analysis of isotopes to identify carbon sources
Analysis of the stable carbon isotopes in carbon dioxide helps to identify the sources and sinks of CO2 in the atmosphere such as fossil fuel combustion, forest fires or the oceans. Such data are also used for developing models for CO2 global budget analysis. To enable comparing the data from different sources, IRMM has prepared a reference CO2 gas for determining the 13C/12C ratio. It will help the calibration of the different instruments via absolute ratios in well known CO 2 samples.
Sulfur content in fuel
Sulfur remains a major contributor to urban atmospheric pollution. Sulfur dioxide, SO2, is largely responsible for formation of smog or acid rain, and the cause of respiratory diseases. Significant sources of SO2 in urban atmospheres are the sulfuric impurities in fuels like diesel, petrol or jet fuels that are converted mainly to SO2 during combustion. Use of sulfur-free diesel would not only decrease the emissions of SO2 but would also reduce amounts of the other pollutants of car exhaust; the sulfur compounds produced during combustion have strong catalyst-poisoning effects.
The maximum permissible limit of sulfur in fuels has been progressively reduced during the past decades and the recent Directive 2003/17/EC imposes on the European Community market a threshold of 50 mg/kg by 1 January 2005, and of 10 mg/kg by 1 January 2009.
The new limits impose requirements for the petroleum industry and the laboratories of regulatory bodies controlling the quality of fuel on the market. They will need internationally recognised certified reference materials that allow them to fulfil the quality requirements. Therefore, the European Reference Materials consortium - IRMM, Bundesanstalt für Materialforschung und -prüfung (BAM, DE) and LGC Limited (UK) - have now initiated a project to produce a European Reference Material (ERM®) of sulfur in fuel.
As for for measuring the sulfur content in diesels, the Joint European Programme for Primary Isotopic Measurements, where IRMM collaborates with BAM and LGC, develops specific methodology based on isotope dilution inductively coupled plasma (ICP) mass spectrometry. IRMM has also benchmarked its own measurements of sulfur content with the national reference laboratories’ results by participating in a Key Comparison of the Comité Consultatif pour la Quantité de Matière (CCQM-K35).