Subsequent key comparison of the pH of a borate buffer

Main text The regional key comparison registered under the EURAMET No. 1619 and the KCDB ID EURAMET.QM-K19.2018 was a subsequent comparison of CCQM-K19.2018. It was organized mainly for European institutes that either could not participate in the CCQM-K19.2018 or could not provide results due to the ramifications of the corona pandemics in 2021. The comparison was performed to demonstrate the capability of the participating institutes to measure pH of borate buffer (pH ~ 9.2) at 15 °C, 25 °C and 37 °C, optionally at 5 °C and 50 °C. The institutes could use a method of their choice, but the use of a method of the highest available level was expected. The results of PTB and NMIJ were used as a link to the KCRV of the original CCQM-K19.2018. Good agreement of the results was demonstrated by most of the participants. 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).