Edgar Flores et al 2012 Metrologia 49 08005 doi:10.1088/0026-1394/49/1A/08005
Edgar Flores1, Faraz Idrees1, Philippe Moussay1, Joële Viallon1, Robert Wielgosz1, Teresa Fernández2, Sergio Ramírez2, Andrés Rojo2, Uehara Shinji3, Jari Waldén4, Michela Sega5, Oh Sang-Hyub6, Tatiana Macé7, Cedric Couret8, Han Qiao9, Damian Smeulders10, Franklin R Guenther11, William J Thorn III11, James Tshilongo12, Napo Godwill Ntsasa12, Viliam Štovcík13, Miroslava Valková13, Leonid Konopelko14, Elena Gromova14, Gerard Nieuwenkamp15, Rob M Wessel15, Martin Milton16, Alice Harling16, Gergely Vargha16, Dirk Tuma17, Anka Kohl17 and Gert Schulz17
Show affiliationsThere is a high international priority attached to activities which reduce NOx in the atmosphere. The current level of permitted emissions is typically between 50 µmol/mol and 100 µmol/mol, but lower values are expected in the future. Currently, ambient air quality monitoring regulations also require the measurement of NOx mole fractions as low as 0.2 µmol/mol. The production of accurate standards at these levels of mole fractions requires either dilution of a stable higher concentration gas standard or production by a dynamic technique, for example one based on permeation tubes.
The CCQM-K74 key comparison was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities and standards for nitrogen dioxide (NO2) at a nominal mole fraction of 10 µmol/mol.
The measurements of this key comparison took place from June 2009 to May 2010.
Seventeen laboratories took part in this comparison coordinated by the BIPM and VSL. The key comparison reference value was based on BIPM measurement results, and the standard measurement uncertainty of the reference value was 0.042 µmol/mol.
This key comparison demonstrated that the results of the majority of the participants agreed within limits of ±3% relative to the reference value. The results of only one laboratory lay significantly outside these limits. Likewise this comparison made clear that a full interpretation of the results of the comparison needed to take into account the presence of nitric acid (in the range 100 nmol/mol to 350 nmol/mol) in the cylinders circulated as part of the comparison, as well as the possible presence of nitric acid in the primary standards used by participating laboratories.
Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.
The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).
Issue 1A (Technical Supplement 2012)
Edgar Flores et al 2012 Metrologia 49 08005
E F Arias and W Lewandowski 2011 Metrologia 48
W Lewandowski and E F Arias 2011 Metrologia 48 S219
B Andreas et al 2011 Metrologia 48 S1
Z Jiang et al 2011 Metrologia 48 246
Joële Viallon et al 2011 Metrologia 48 08018
Thomas J Witt and N E Fletcher 2010 Metrologia 47 616
Joële Viallon et al 2010 Metrologia 47 08024
D T Burns and L Büermann 2009 Metrologia 46 S9
L Büermann and D T Burns 2009 Metrologia 46 S24