Accurate measurements of sulphur dioxide at the concentrations found in ambient air have become essential to support monitoring and legislation concerned with air quality. In general, the primary element of quality assurance for field instruments is regular calibration using certified gas mixtures. The concentration range chosen for this Key Comparison (240 nmol/mol to 320 nmol/mol) is defined by appropriate European standards and is typical of similar levels used around the world. The travelling standards used for the comparison were prepared commercially by a supplier with a proven track record of preparing stable mixtures of the relevant gases. The coordinating laboratory (NPL) carried out stability checks on the mixtures and determined the amount fraction using a primary gravimetric permeation facility. These data were used to determine the drift rate (and uncertainty) of each standard. The results for the 11 participants in CCQM-K26.b and the one participant in CCQM-P50.b are presented in this report. Degrees of equivalence have been calculated based on a reference value (corresponding to the KCRV) derived from the primary gravimetric facility used by the coordinating laboratory.

MARUYAMA Masaaki;  NOVAK Jiri;  WALDEN Jari;  DIAS Florbela;  BOROWIAK Annette;  LAGLER Friedrich;  SEONG KIM Jin;  MACE Tatiana;  GUENTHER Franklin R.;  VAN DER VEEN Adriaan;  MILTON Martin;  LEGGETT Graham;  MEDEM Anneliese;  STUMMER Volker;  KUSTIKOV Yuri A.;  KONOPELKO Leonid A.;  EFREMOVA Olga;  FROEHLICH Marina; 

2007-05-15

IOP PUBLISHING LTD

JRC34357

0026-1394,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC34357,   

10.1088/0026-1394/44/1A/08007,