The Chemistry section has consolidated its programme in gas metrology in support of the international comparability of gas standards for air quality and greenhouse gas monitoring, and in primary calibrator comparisons for organic analytes in support of clinical, food analysis and forensic applications. The Section is running or has completed six international comparisons in support of these areas during the time period covered by the report. The BIPM Chemistry section actively supports the Consultative Committee for Amount of Substance (CCQM), participating in its yearly meetings and biannual meetings of its working groups.
The first two year cycle of the on-going key comparison BIPM.QM-K1 – Ozone at ambient level – was launched in January 2007, and since July 2007, eight laboratories have brought their ozone standards to the BIPM, and two others have participated in linking RMO comparisons. Two national ozone reference standards have had upgrade kits fitted to them in order to correct for systematic biases identified by the BIPM and the NIST.
The programme to develop a candidate primary ozone photometer based on a laser light source has continued, with a strong focus on reducing the noise level of the system. The frequency doubling crystal included in the argon laser head has been replaced by one at the shorter wavelength of 244 nm, and measured ozone mole fractions are within 5 % of the values obtained using the Hg lamp-based standard reference photometer (SRP).
A third validation study of the NO2 facility in support of the BIPM coordinated pilot study (CCQM-P110 – Nitrogen dioxide 10 µmol/mol) has been completed. It includes the comparison of five NO2 primary gas standards with dynamic gas mixtures produced by the NO2 facility, and on-line measurements using the FTIR facility, which has been improved.
The final report of the BIPM coordinated study, CCQM-P73 on nitrogen monoxide standards, performed over the period August 2006 – October 2007, was published in the Metrologia Technical Supplement.
The Organic Analysis Programme within the Chemistry section coordinates CCQM comparisons of the purity assessment of organic compounds, for use as primary calibrators. The analytical capabilities within the Programme were enhanced in 2007-2008 by the acquisition of a photo-ionisation source for use with the existing QTrap LC-MS/MS system, a stand-alone Agilent Rapid Resolution LC-UV system and a dynamic vapour sorption balance.
Development and validation of analytical methods required for use in the characterization and production of the cardiac glycoside CCQM-P20.f pilot study material have been completed, and validation activities broadened to incorporate the planned CCQM-K55.a key comparison on pure steroid hormones.
In the second half of 2007, the homogeneity and stability assessments of the digoxin candidate materials for CCQM-P20.f, the second CCQM comparison coordinated by BIPM, were completed, and the material distributed to NMIs. A significant level of residual organic solvent was also present in the material, but detected only by a small number of laboratories. The Draft B report is currently in preparation.
The first round of the organic purity assignment key comparison, CCQM-K55.a, will be coordinated by the BIPM. The steroid 17β-estradiol will be the principal component of the study material. The candidate material has been prepared by and supplied to the BIPM by collaborators from the Organic Analytical Chemistry division at the NMIJ (Japan), and is currently undergoing characterization at the BIPM.
As part of their planning for future key comparisons, the CCQM Organic Analysis Working Group (OAWG) identified purity assessment as being a core technical capability. The OAWG has recommended that participation in CCQM-K55 be compulsory for all NMIs which have activities or make CMC claims in the area of organic analysis.
As part of the activities in support of the JCTLM, a symposium on ‘Activities and Challenges for Traceability and Standardization in Laboratory Medicine’ was organized in Beijing in October 2007, in collaboration with colleagues from the NIM and the NIST. Procedures for the operation of the JCTLM Secretariat were presented to the JCTLM Executive for their approval, during their sixth meeting. The JCTLM Database website available at http://www.bipm.org/jctlm/ was modified to include the reference measurement laboratory services as a searchable category to the database. The total number of external connections to the JCTLM Database website has increased from July 2007 to May 2008. This corresponds to about 1300 visits each month as of May 2008.
A workshop on ‘Method Performance and Measurement Uncertainty’ was organized by the BIPM Chemistry section in collaboration with other international organizations for Government delegates to the Codex Alimentarius Commission's Committee on Methods of Analysis and Sampling in April 2008.
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