This report describes key comparison APMP.QM-K4 that was held under the auspices of the Asia Pacific Metrology Program (APMP) Technical Committee for Amount of Substance (TCQM) in 2000–2001, and piloted by the NMIJ. The report was checked by the CCQM Working Group on Gas Analysis and approved by the CCQM. Four national metrology institutes, CSIR-NML (South Africa), CMS-ITRI (Taiwan), KRISS (Republic of Korea) and NMIJ/CERI (Japan) participated in the key comparison. ERL-HIAST (Syria) participated as a 'study' and the results will not be included in MRA Appendix B. The protocol used is equivalent to that of the CCQM-K4, and the link laboratory is NMIJ. Gas mixtures of ethanol in air with a nominal amount-of-substance fraction of 120 µmol/mol were prepared in cylinders using the gravimetric method by CERI. One cylinder was delivered to each participant and analysed based on the participant's standard. Two of the participants have their own gravimetric primary standards, one carried out the analysis using the standard by a static volumetric method, and two purchased gravimetrically mixed gases in cylinders from other national laboratories for their standards. This key comparison demonstrates that the level of comparability between three of the four participants is adequate to meet the requirements for ethanol/air mixtures at this amount-of-substance fraction.

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 Mutual Recognition Arrangement (MRA).