{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,11]],"date-time":"2026-02-11T15:00:52Z","timestamp":1770822052822,"version":"3.50.1"},"reference-count":25,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2020,7,9]],"date-time":"2020-07-09T00:00:00Z","timestamp":1594252800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100014132","name":"European Metrology Programme for Innovation and Research","doi-asserted-by":"publisher","award":["17FUN09"],"award-info":[{"award-number":["17FUN09"]}],"id":[{"id":"10.13039\/100014132","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002301","name":"Eesti Teadusagentuur","doi-asserted-by":"publisher","award":["PRG690"],"award-info":[{"award-number":["PRG690"]}],"id":[{"id":"10.13039\/501100002301","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["TK141"],"award-info":[{"award-number":["TK141"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","award":["UID\/QUI\/00100\/2020"],"award-info":[{"award-number":["UID\/QUI\/00100\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>A unified pH scale of absolute values (pHabs scale) enables the comparison of acidities in different solvents. To date, very few different experimental setups have been used for the measurement of values on this scale. The article describes the design and performance of the different symmetric cells used for unified pH measurement by several institutions. Well-established and reliable standard aqueous buffer solutions are the first step of method validation necessary to achieve a robust metrological level for more complex media. The pH of aqueous standard buffers was measured by differential potentiometry, where the potential between two glass electrodes is measured directly. All the tested electrochemical cells prove to be suitable for unified pH measurements. This validation highlights that the method is, to a large extent, independent of the used equipment, including the cell geometry. The inherent symmetry of the cell design helps to reduce the experimental workload and improve the accuracy of obtained results.<\/jats:p>","DOI":"10.3390\/sym12071150","type":"journal-article","created":{"date-parts":[[2020,7,10]],"date-time":"2020-07-10T09:45:31Z","timestamp":1594374331000},"page":"1150","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Symmetric Potentiometric Cells for the Measurement of Unified pH Values"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0893-8015","authenticated-orcid":false,"given":"Agnes","family":"Heering","sequence":"first","affiliation":[{"name":"Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany"},{"name":"Institute of Chemistry, University of Tartu (UT), 14a Ravila Street, 50411 Tartu, Estonia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6748-552X","authenticated-orcid":false,"given":"Daniela","family":"Stoica","sequence":"additional","affiliation":[{"name":"Laboratoire National de M\u00e9trologie et d\u2019Essais (LNE), 1 Rue Gaston Boissier, 75015 Paris, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8582-8904","authenticated-orcid":false,"given":"Filomena","family":"Cam\u00f5es","sequence":"additional","affiliation":[{"name":"FCi\u00eancias. ID (FC.ID), Centro de Qu\u00edmica Estrutural, Faculdade de Ci\u00eancias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1987-5486","authenticated-orcid":false,"given":"B\u00e1rbara","family":"Anes","sequence":"additional","affiliation":[{"name":"FCi\u00eancias. ID (FC.ID), Centro de Qu\u00edmica Estrutural, Faculdade de Ci\u00eancias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal"}]},{"given":"D\u00e1niel","family":"Nagy","sequence":"additional","affiliation":[{"name":"Government Office of the Capital City Budapest (BFKH), N\u00e9metv\u00f6lgyi \u00fat 37-39, 1124 Budapest, Hungary"}]},{"given":"Zs\u00f3fia","family":"Nagyn\u00e9 Szil\u00e1gyi","sequence":"additional","affiliation":[{"name":"Government Office of the Capital City Budapest (BFKH), N\u00e9metv\u00f6lgyi \u00fat 37-39, 1124 Budapest, Hungary"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6827-1550","authenticated-orcid":false,"given":"Raquel","family":"Quendera","sequence":"additional","affiliation":[{"name":"Instituto Portugu\u00eas da Qualidade (IPQ), R. Ant\u00f3nio Gi\u00e3o, 2, 2829-513 Caparica, Portugal"}]},{"given":"Lu\u00eds","family":"Ribeiro","sequence":"additional","affiliation":[{"name":"Instituto Portugu\u00eas da Qualidade (IPQ), R. Ant\u00f3nio Gi\u00e3o, 2, 2829-513 Caparica, Portugal"}]},{"given":"Frank","family":"Bastkowski","sequence":"additional","affiliation":[{"name":"Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany"}]},{"given":"Rasmus","family":"Born","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, University of Tartu (UT), 14a Ravila Street, 50411 Tartu, Estonia"}]},{"given":"Jaak","family":"Nerut","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, University of Tartu (UT), 14a Ravila Street, 50411 Tartu, Estonia"}]},{"given":"Jaan","family":"Saame","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, University of Tartu (UT), 14a Ravila Street, 50411 Tartu, Estonia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7928-6125","authenticated-orcid":false,"given":"Silvie","family":"Lainela","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, University of Tartu (UT), 14a Ravila Street, 50411 Tartu, Estonia"},{"name":"Laboratoire National de M\u00e9trologie et d\u2019Essais (LNE), 1 Rue Gaston Boissier, 75015 Paris, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8008-1012","authenticated-orcid":false,"given":"Lokman","family":"Liv","sequence":"additional","affiliation":[{"name":"The Scientific and Technological Research Council of Turkey\u2013National Metrology Institute (TUBITAK UME), Gebze Campus, Gebze 41470, Turkey"}]},{"given":"Emrah","family":"Uysal","sequence":"additional","affiliation":[{"name":"The Scientific and Technological Research Council of Turkey\u2013National Metrology Institute (TUBITAK UME), Gebze Campus, Gebze 41470, Turkey"}]},{"given":"Matilda","family":"Rozikov\u00e1","sequence":"additional","affiliation":[{"name":"Czech Metrology Institute (CMI), Okru\u017en\u00ed 31, 63800 Brno, Czech Republic"}]},{"given":"Martina","family":"Vi\u010darov\u00e1","sequence":"additional","affiliation":[{"name":"Czech Metrology Institute (CMI), Okru\u017en\u00ed 31, 63800 Brno, Czech Republic"},{"name":"Slovak University of Technology, Faculty of Mechanical Engineering, Namestie Slobody 17, SK-81231 Bratislava 1, Slovakia"}]},{"given":"Alan","family":"Snedden","sequence":"additional","affiliation":[{"name":"DFM A\/S, Kogle All\u00e9 5, 2970 H\u00f8rsholm, Denmark"}]},{"given":"Lisa","family":"Deleebeeck","sequence":"additional","affiliation":[{"name":"DFM A\/S, Kogle All\u00e9 5, 2970 H\u00f8rsholm, Denmark"}]},{"given":"Valentin","family":"Radtke","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Anorganische und Analytische Chemie, University of Freiburg, Albertstr. 21, 79104 Freiburg, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7182-4387","authenticated-orcid":false,"given":"Ingo","family":"Krossing","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Anorganische und Analytische Chemie, University of Freiburg, Albertstr. 21, 79104 Freiburg, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3000-4964","authenticated-orcid":false,"given":"Ivo","family":"Leito","sequence":"additional","affiliation":[{"name":"Institute of Chemistry, University of Tartu (UT), 14a Ravila Street, 50411 Tartu, Estonia"}]}],"member":"1968","published-online":{"date-parts":[[2020,7,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2169","DOI":"10.1351\/pac200274112169","article-title":"Measurement of pH. 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