{"term":{"id":"11548","title":"zone pH","longtitle":"IUPAC Gold Book - zone pH","doi":"10.1351\/goldbook.11548","code":"11548","status":"current","definitions":[{"id":1,"text":"pH of the solute zone in pH-zone-refining counter-current chromatography. \\[{\\rm{pH}}_{\\rm{zone}} = \\pu{p}K_{\\rm{a}} + \\log[(K_{\\rm{DS}}\/K_{\\rm{S}}) - 1]\\], where \\(K_{\\rm{DS}}\\) is the partition ratio of solute $\\ce{S}$ (an indicator for solute hydrophobicity) and \\(K_{\\rm{S}}\\), the dissociation constant of the solute.","notes":{"1":"According to theoretical analysis two solutes that differ their zone \\(\\pu{pH}\\) values by \\(\\pu{0.2}\\) or greater can be resolved in \\(\\pu{pH}\\)-zone-refining CCC."},"contexts":[],"links":[{"term":"pH-zone-refining counter-current chromatography","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/09947"}],"sources":["PAC, 2017, 90, 181. 'Terminology of separation methods (IUPAC Recommendations 2017)' on page 205 (https:\/\/doi.org\/10.1515\/pac-2017-0111)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/11548\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/11548\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/11548\/plain"},"citation":"Citation: 'zone pH' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351\/goldbook.11548","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2026-04-21T11:12:43+00:00"}}