Ammonia is an important compound in the chemical industry. It is widely used and is the basis for producing other compounds containing nitrogen. Ammonia is also very hazardous, and consequently emissions of ammonia need be controlled and monitored. In the past years, several national metrology institutes have developed facilities for the preparation of Primary Standard gas Mixtures (PSMs), dynamically generated ammonia mixtures and facilities for comparing and certifying gas mixtures containing ammonia.The amount-of-substance fraction level of ammonia chosen for this key comparison is 30–50 µmol/mol. The results of this key comparison revealed that there is at present no consensus among static and dynamic techniques for gas mixture preparation for this component in this range. As key comparison reference value (KCRV), the mean of the three methods is used. In its uncertainty, no allowance is made for the observed biases. With respect to the KCRV, only two laboratories report consistent results. When grouped in accordance with the employed methods, the results are consistent. Further experimental work is needed.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).

The aim of this comparison was to compare capabilities for the preparation and value assignment of gas mixture standards for ethanol in nitrogen, maintained at national metrology institutes (NMIs). The measurements in this key comparison took place in 2006. There were three participants and one coordinating laboratory. The key comparison reference value (KCRV) was based on the gravimetric preparation for all components. The range of the nominal amount-of-substance fractions of the comparison standard is 100 µmol/mol to 130 µmol/mol. The Chemical Evaluation Research Institute (CERI, Japan) prepared gravimetric mixture samples of ethanol in nitrogen in 10 L aluminium cylinders and the homogeneity and long-term stability of these samples were evaluated at CERI before and after the shipment of the cylinders to the participants. Each participating laboratory was shipped one cylinder to be analyzed and then returned to the CERI. Each sample was reanalyzed to verify whether the contents were stable throughout the comparison. These measurements showed no significant change in the amount fraction within the estimated uncertainty of the measurements. Two of the three participants submitted results that were within 0.1% of the relevant reference value. In these cases, the estimated uncertainty was larger than the deviation from the reference value. CERI was the link laboratory between CCQM-K4 and APMP.QM-K4.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).

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