International comparison CCQM K52: carbon dioxide in synthetic air

Abstract

61 p. : il.The first key comparison on carbon dioxide in nitrogen dates from 1993-1994 (CCQM-K1b) [1]. It is in fact one of the first types of gas mixtures that was used in an international (key) comparison. Since then, numerous National Metrology Institutes (NMIs) have been setting up facilities for gas analysis, and have developed claims for their Calibration and Measurement Capabilities (CMCs) for these mixtures. Also, in 2003 a comparison (CCQM-P41 [2, 3]) was carried out between NMIs and WMO laboratories for the determination of greenhouse gases showing a good overall agreement between the participants. In the April 2005 meeting of the CCQM Gas Analysis Working Group, a policy was proposed to repeat key comparisons for stable mixtures every 10 years. Consequently, this comparison is consistent with the proposed policy and enables NMIs that could not participate in the previous comparison to take part. This report describes the results of a key comparison for carbon dioxide in synthetic air (oxygen + nitrogen). The amount–of–substance fraction level of carbon dioxide chosen for this key comparison (360 μmol/mol) represents the ambient level of this component in air. This key comparison aims to support CMC-claims for carbon dioxide in both nitrogen or air (synthetic and purified) from 100 μmol/mol to 20 cmol/mol