Report of the comparison BIPM.QM-K2.b, on carbon dioxide in nitrogen at ambient levels, with E+ E Elektronik (2025)

Main text As part of the ongoing key comparison BIPM.QM-K2.b, a comparison has been performed on the amount fraction of carbon dioxide (CO 2 ) in nitrogen, in gaseous reference materials value assigned by the designated institute of Austria E+E Elektronik (E+E), with the key comparison reference value based on measurements performed with the comparison reference facility maintained at the Bureau International des Poids et Mesures Headquarters (BIPM). Three standards were used for this comparison, which cover a CO 2 amount fraction range of 350 μmol mol −1 to 800 μmol mol −1 . 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 https://www.bipm.org/kcdb/ . 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).