Final report on subsequent key comparison CCQM-K18.1: pH of carbonate buffer

Abstract

The subsequent key comparison CCQM-K18.1 was started in order to evaluate the equivalence of metrology institutes as a follow-up to the previous key comparison CCQM-K18 for institutes that could not take part in the comparison at that time or did not consider their results representative of their capabilities. A carbonate buffer of a slightly different composition to that in CCQM-K18 was used.There were seven institutes plus the coordinating laboratory participating in this subsequent comparison. Most of the participating institutes showed significant improvement; in some cases the new results confirmed the previous ones. The reasons for this have still to be elucidated. 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).

“Degrees of equivalence” for chemical measurement capabilities: primary pH

“…The data used in this study are the results of primary method pH measurements as provided in the published Final Reports [3][4][5][6][7][8][9][10][11][12][13] of the KCs listed in Table 1. All of the primary pH measurement data given in these reports are listed in Tables S1.a to S5.a of the electronic supplementary material (ESM), with the exception of values that (1) were identified in the KC's final report as technically flawed and as such were excluded from the reference value (RV) estimation process for that KC and (2) are not the most recent primary pH measurement in that buffer system for the NMI that submitted the excluded result.…”