Robert I Wielgosz et al 2008 Metrologia 45 08002 doi:10.1088/0026-1394/45/1A/08002
Robert I Wielgosz1, Michael Esler1, Joële Viallon1, Philippe Moussay1, Sang Hyub Oh2, Byung Moon Kim2, Angelique Botha3, James Tshilongo3, Ipeleng S Mokgoro3, Masaaki Maruyama4, Tatiana Mace5, Christophe Sutour5, Viliam Stovcík6, Miroslava Valková6, Stanislav Musil6, Alejandro Pérez Castorena7, Victor Serrano Caballero7, Francisco Rangel Murillo7, Leonid A Konopelko8, Yury A Kustikov8, Vladimir V Pankratov8, Elena V Gromova8, William J Thorn9, Franklin R Guenther9, Damian Smeulders10, Gonçalo Baptista11, Florbela Dias11, Rob M Wessel12, Gerard Nieuwenkamp12 and Adriaan M H van der Veen12
Show affiliationsThe pilot study evaluated the level of comparability of laboratories' preparative capabilities for gravimetric nitrogen monoxide/nitrogen primary reference mixtures in the range (30–70) µmol/mol. The comparison was designed so that measurements would be performed at a central laboratory (the BIPM) and measurement results compared to values assigned by each national metrology institute (NMI) based on gravimetry using regression analysis.
The advantages and complications in organizing a comparison with measurements performed at a central laboratory have been clearly demonstrated, notably:
Following FTIR analysis, the standards of three laboratories (six gas standards in total) were omitted from the regression analysis data set, as a significant difference between reported and measured values of impurity contents was observed. An additional standard was removed from the regression analysis set as its deviation from the regression line was of the same order of magnitude as the standards already omitted. A regression line consistent with the remaining calibration data (15 gas standards) could be obtained by increasing estimates of the coordinating laboratory's measurement uncertainty by approximately a factor of three, resulting in analytical standard uncertainties of 0.12% (at 70 µmol/mol) and 0.27% (at 30 µmol/mol), and predicted standard uncertainties of the nitrogen monoxide mole fractions of 0.09 µmol/mol. Reported standard uncertainties related to gravimetric preparation ranged from 0.004 µmol/mol to 0.11 µmol/mol with a median of 0.03 µmol/mol. Nevertheless, comparison of the results of CCQM-P73 to previous key comparisons for nitrogen monoxide in nitrogen at 100 µmol/mol (CCQM-K1.c and EUROMET.QM-K1.c) illustrates the reductions in uncertainties that can be achieved through a comparison with measurements performed at a central facility.
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The final report has been peer-reviewed and approved for publication by the CCQM-GAWG.
Issue 1A ( 1 January 2008)
Robert I Wielgosz et al 2008 Metrologia 45 08002