Final report on COOMET.QM-K76 (COOMET project no 484/RU/09): Key comparison of primary standard gas mixtures: SO2 in nitrogen (100 µmol/mol)

Sulfur dioxide is one of the main contaminants present in the atmosphere due to burning of coal, oil and natural gas, smelting of base metals and production of sulfuric acid. Sulfur dioxide has been the subject of three previous CCQM key comparisons: CCQM-K1.d in 1997, CCQM-K26.b in 2005 and CCQM-K76 in 2010. VNIIM proposed a new COOMET project (No 484/RU/09) in this field, which was registered in the KCDB as key comparison COOMET.QM-K76. It was found that all results were consistent with the reference (gravimetric) values, with observed differences not exceeding ?0.60% and not exceeding either the appropriate assigned expanded uncertainties. VNIIM is the linking laboratory to CCQM-K76. SMU has improved the results obtained in CCQM-K76. The mixtures prepared for this exercise were found to be stable during about one year within the uncertainty of the measurements. 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 (CIPM MRA).