Final report on CCQM-K19.1: pH of borate buffer

• Published in: Metrologia Vol. 48; p. 1
• Main Authors: Spitzer, P, Adel, B, Meyer, J, Matzke, J, Gonzaga, F B, Borges, P P, Dias, J C, Hongyu, X, Bing, W, Jakobsen, P T, Champion, R, Ohata, M, Maksimov, I, Hioki, A, Vyskocil, L, Mariassy, M, Pratt, K
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2011
• Subjects: Acidity; Chemical compounds; Comparative analysis; Measurement techniques
• ISSN: 0026-1394; 1681-7575

The subsequent key comparison CCQM-K19.1 was carried out in 2010 as a follow-up comparison to CCQM-K19. Three laboratories (NMIJ, PTB and SMU) took part in both comparisons. Their results are consistent. The assigned uncertainties are reliable and of the same order. These results provide the link to CCQM-K19. As well as the original comparison the subsequent key comparison was organized to demonstrate the capability of the interested national metrology institutes to measure the pH value of an unknown borate buffer by a primary method at 15 °C, 25 °C and 37 °C. Eight laboratories took part in CCQM-K19.1. The participants either were not able to participate in the original comparison or participate only in the Pilot Study CCQM-P82 running in parallel to CCQM-K19. In one case the laboratory expressed doubts on the integrity of the sample provided in CCQM-K19. The result in CCQM-K19.1 is the acidity function at zero chloride molality of the unknown borate buffer solution. Most participants in the key comparison CCQM-K19.1 demonstrated improved capabilities. This especially applies to the laboratories that had originally taken part in the pilot study CCQM-P82. In some cases previous results could be confirmed. The hidden reasons for that have still to be clarified. [PUBLICATION ABSTRACT]