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Metrology in chemistry and traceability

Objective

Specific Objectives

- To support European and other international organisations in setting up an internationally structured system for chemical measurements;

- To supply the EU with the best possible isotopic reference measurements and materials as and when required;

- To achieve trace ability of EU measurements of amount of substance to the Avogadro Constant, within the overall framework of trace ability to the SI (Système International d'Unités) system;

- To represent the EU in this (the above) mandate and assume a leading role in the execution of this mandate.
Planned Deliverables

- Providing customers with a vital link in the chain of metrology and trace ability of chemical measurements;

- Supporting the implementation of EU policies (e.g. quality of measurements in trade & commerce) and to underpin the open market;

- Training of DG staff dealing with EU Directives the basics of metrology;

- Validated method for oxygen isotope ratios in organic compounds;

- Calcium and zinc IRMs.

Summary of deliverables made by: 31/12/2001
Contribution to CCQM programme BIPM-CCQM, EUROMET, EA and DG TRADE
IRMM is signatory of the Mutual Recognition Arrangements and offers EU support in setting up appropriate internationally structured measurement systems.
IRMM participated in two CCQM Working Group meetings, the CCQM president meeting (Gaithersburg, USA, 10 March 2001), the CCQM plenary meeting (Sevres, FR, 2-6 April 2001) and the "inter-regional meeting" concerning chemistry CMCs (BIPM, Paris, 6-8 August 2001).
Draft reports were prepared for the CCQM-K13 key comparison (Cd and Pb in sediment), the CCQM-P12 study (Pb in wine) and status reports were prepared for CCQM-P26 (S in Fuel), CCQM-P14 (Ca in serum) and CCQM-P29 (Cd and Zn in rice) studies. Samples were distributed for the CCQM-P26 (S in Fuel) and CCQM-P14 (Ca in serum) studies and agreement was obtained on the KCRV and equivalence statements for the CCQM-K13 key comparison. Samples and information packages for the CCQM-K24 (Cd in rice) key comparison and CCQM-P29 were also prepared and distributed and finally the Draft B" of the CCQM-K13 was prepared and distributed.
The Inorganic Analysis Working Group meeting was organised and hosted at IRMM from 23-24 October 2001.

Contribution to EUROMET METCHEM programme EUROMET
IRMM represents the Commission in EUROMET and offers EU support in setting up appropriate internationally structured measurement systems.
IRMM is the organising laboratory for 6 EUROMET projects and the progress on these was reported at the EUROMET MetChem meeting (Bratislava, Slovakia, 13-14 February 2001). Samples for EUROMET projects 566 (S in fuel) and 563 (Ca, glucose and creatinine in serum) were distributed to participants and IRMM CMC claims for the appendix C of the MRA were submitted. Samples and information packages for EUROMET projects 528 (Cd and Pb in water) and 565 (Cd and Zn in rice) were also prepared and submitted and final reports were prepared for EUROMET projects 548 (Pb and Cd in sediment) and 568 (Pb in wine).

Contribution to CITAC programme CCQM, EURACHEM, EA and EUROMET
IRMM is currently hosting the secretariat of CITAC.
The CITAC annual newsletter was compiled, printed and distributed to 2800 scientists all over the world. The minutes of the 12th CITAC meeting (Gaithersburg, USA, 12 March 2001) were produced, finalised and sent to the CITAC members. The scientific programmes for the CITAC symposium in Athens (Greece, 3rd September 2001), the CITAC session at the IMA conference (Ioannina, Greece, 5th September 2001) and the CITAC meeting in Athens, Greece (4th September 2001) were prepared.

Primary Isotopic Gas Standards (PIGS) IAEA, Member State labs in isotopic measurements
PIGS enable SI traceable isotope ratios to be obtained in areas of food, clinical, atmospheric and environmental isotopic measurements.

- Sulphur PIGS: The SF6 certificate was prepared and completed.

- SO2 PIGS: The problems with yields for the conversion of SO2 to SF6 were solved (now~95%) and at present isobaric instrumental effects are being tested in Beijing, China.

- CO2 PIGS: Certificates for the two series of CO2 bottles were drafted and certificates for IMEP-8A, and IMEP-8B containing delta values were finalised.

- Exploratory 13C/12C and 18O/16O on natural products via CF4 and O2:
Troubleshooting of the fluorination procedure was carried out, the critical step was found and the procedure was modified and optimised. Three different types of graphites were fluorinated resulting in >90% carbon recovery in the form of gaseous fluorides of which 90% is CF4. The optimised procedure was checked for blank contributions and systematic isotope effects. Isotopic measurements were carried out on the fluorination products of three different types of graphite. Absolute values for carbon isotope ratios obtained via the CF4 route show a gap of more than 15 ‰ compared to those obtained for CO2 (from IMEP 8). A dual inlet was installed on the MAT delta XLS for the measurements of gas and a manuscript was written dealing with the conversion of carbon into CF4 and its use for carbon isotope ratio measurements. Experiments were performed to convert carbon from sugars, cellulose and polyethylene (IAEA PEF1) into CF4. First comparisons between carbon isotope ratios obtained after conversion into CF4 and CO2 have also been started.

Avogadro project PTB, IMGC, NRLM
International collaboration aimed at redefining the kilogram.
A new MAT 271 spectrometer was installed in IRMM, made operational and first tests are ongoing.
New Si synthetic isotope mixtures have been prepared by mixing enriched SiF4 in gaseous form, as an independent check on the large residual k-factors which have traditionally been used. So far however, uncertainties are only in the 10-3 range with weighing as the major uncertainty source.
The different conversions from BaiSiF6 into iSiF4 were successful so the oxyfluorides problem and lower conversion yields problem are now solved. Finally a meeting in Tsukuba (Oct 2001) was held and all major contributors to this project met. A detailed road map for the future was drafted.

Measurement of copper in Avogadro silicon crystals
Measurements of the degree of imperfection (voids and interstitials) in single crystal, by thermal diffusion of copper in silicon, are required for the Avogadro project.
The digestion of three Si cubes and measurements thereafter led to in depth investigations to rule out Cu contamination. Discussions on this were held with Harvard University and further experimental work was carried out with the conclusion that the contamination issue is not entirely solved but it is at an acceptable level and more stable. A decision is taken with Harvard University to proceed with the second phase of the project (Cu diffusion in the Si cubes). The preparatory work for the second phase (conditioning the cubes and preparation of quartz cells) started.

Isotopic Reference Materials (IRMs) 86/278/EEC; 98/83/EC; 94/62/EC NMis and MS labs
Anchors to facilitate the promotion of Metrology in Chemistry.

- Certification Cr spike IRM: Revision of the uncertainty calculations was completed; the file was reviewed and transmitted for completion of the certificates. The certificates are presently being reviewed.

- Certification Zn spike IRM: gravimetrical work was carried out and the Zn material measured at Beijing University, has been obtained. This material has calibrated values and these will later on be compared with the IRMM values.

- Certification S spike IRM: New measurement of IRMM-646 were performed and the evaluation is ongoing. Reviewing of the certificates for the reference materials IRMM-643, 644 and 645 as well as IM-6002, 6003 commenced and is presently ongoing.

- Preparation of Ba spike: the ampoules were labelled and the certificate and the certification report was written and signed thereby completing this project task.

- Preparation of a Tl spike: Ampouling the spike was completed and the final report has been prepared and signed thereby completing this task.

- Preparation of a Ca spike: The isotopically enriched materials, to be used for the reference materials IRMM-656, 657, 658 and 008/x have been vacuum distilled at EMPA St. Gallen. A 48Ca material was added to the project. Two spike materials (one with natural isotopic composition, IM-6008, and one enriched in 44Ca, IM-6009) have been dissolved and put into ampoules. Blends for IDMS measurement of the amount content of IM-6009 have also been prepared. The distilled material was sent from EMPA to IRMM.

41Ca isotopic calibrants for 5FWP SCA on OSTEODIET Univ. Cork (IE), ETH Zurich
Impact of Diet and Gene-Nutrient Interactions on Calcium and Bone Metabolism (1999/C 64/14) for the prevention of osteoporosis.
This project commenced in 2000. The 41Ca arrived from the U.S.A. The check on gamma-ray emitting impurities was performed (contained small amounts of 60Co, 40K, 133Ba, 137Cs and 138La). A check on Ca - Ni separation was also performed (NiS precipitation, CaC2O4 precipitation or Ni-Dimethylglyoxim precipitation). Separation work commenced and completed. Blends of the 41Ca solution were prepared by mixing with IM-6009 (44Ca enriched material). 88 grams of the 41Ca solution was sent to ETH in Zurich and from the 3g remaining at IRMM, 2g were used to prepare reference materials for the osteoporosis project. Measurements of the isotopic composition and amount content are presently ongoing. The remaining 1g will be used for half-life measurements of 41Ca.

Certification for CCQM/IMEP BIPM-CCQM
Representing the EC in EUROMET, IRMM supports the international effort to demonstrate measurement equivalence, as required by the new Mutual Recognition Agreement.

- CCQM-K13 key comparison (Cd and Pb in sediment). The "IRMM way" of evaluating the combined uncertainties attached to these measurements was presented in detail at the BIPM.

- CCQM-P12: Pb in wine. Results from the other CCQM participants were in excellent agreement with results produced at IRMM.

- CCQM-P29: Cd in rice. This round will has been accepted and converted into a key-comparison exercise (K-24). Certification measurements completed.

- CCQM P14 (Ca in human serum): A TIMS measurement method was developed and validated and applied to the sample. Certification measurements completed.

Assay of Sulfur in Fuel Directive 1999/32/EC
In accordance to JO L326/35 (3rd Dec 1998), this research will make a metrological tool available for reliable sulfur content measurement via isotope specific techniques.
Blank measurements were completed and the certificates were written and signed. The project was discussed with representatives from NIST and their values are typically 1-2% higher (for the sample with lowest content). Although this difference is small, the values for the two sets of data do not overlap within the uncertainty and thus follow up measurements are required and were planned. A verification measurement was performed using a NIST assay material and the same result was obtained so there will be no changes to the certificate.

Certification of reference materials: NMis and Member State labs
Anchors to facilitate the promotion of a common measurement system.
The re-certification of Cd in CRM 194, CRM-195 and CRM-196 (Bovine blood samples) was performed. The certification of the strontium isotopic composition in an 86Sr enriched solid strontium carbonate material was carried out as well as investigations for the certification of the iodine isotopic composition in 129I enriched solid lead iodide in support to Neutron Physics measurements.

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Output Indicators and Impact

For the Primary Isotopic Gas Standards (PIGS), the production and certification of the isotopic ratios of pure gases will be expanded (e.g. CO2 for accurate monitoring of the carbon fluxes in the atmosphere with DGs ENV, TRADE, the JRC Environment Institute and the climate change cluster). Furthermore, IRMM will calibrate the international carbon and oxygen isotopic measurement scales in close co-operation with the IAEA.
A production and distribution system for Primary Reference Materials will also be established to realise the endpoint of the trace ability chain in a metrology based on chemical measurement systems linking results to the SI, in collaboration with NMIs.
Summary of the project

There is an underlying need to improve the quality of chemical measurements and for the European Commission to provide leadership and co-ordination in this task (see "Metrology in Chemistry", B. King, 1998, EUR 19074 EN, p7). IRMM is a leading institution in the development of a metrological measurement system in chemistry and it has achieved this status through:

- conceptual input to international fora such as BIPM, EUROMET, EURACHEM, CITAC and EA;
- its production and certification of reference material and isotopic reference materials,
- its targeted development of chemical reference methods;
- its International Measurement Evaluation Programmes (IMEP) and;

- its role as signatory of the Mutual Recognition Arrangement (between 39 Metrology Institutes including JRC-IRMM under the auspices of BIPM).

See also the related EU enlargement process pre-accession (pa) project.

Rationale

In the EU alone, 3-4 billion analytical data are being generated annually and the costs of chemical measurements approaches some 100 billion Euro p.a.
Representing the European Commission, IRMM has a mandate to develop a "Scientific Reference System" for chemical measurements within the European Research Area.
Assuming a leading (and growing) role (on behalf of the Commission) for the development of a structured measurement system in chemistry in the EU - IRMM has the potential to pioneer and take on a pro-active role in making available primary chemical calibrants. It also has the neutral status to evaluate measurements on politically sensitive issues (e.g. lead in wine, cadmium in rice) and a long standing expertise in isotopic reference materials and measurements for food, clinical, atmospheric and environmental issues.
To achieve this mandate, the IRMM has the largest isotope mass spectrometry infrastructure in Europe (ThI/EI-MS, ICP-MS) alongside an ultra-clean chemical laboratory (class 5, 120 m², 16 work places, with corrosion resistant construction) and is the world's number one provider of Isotopic Reference Materials.

Funding Scheme

JRC - Joint Research Centre research

Coordinator

Institute for Reference Materials and Measurements
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