zone pH

in counter-current chromatography
symbol: $\rm{pH}_{\rm{zone}}$

https://doi.org/10.1351/goldbook.11548

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.

Note: 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.

Source:
PAC, 2017, 90, 181. 'Terminology of separation methods (IUPAC Recommendations 2017)' on page 205 (https://doi.org/10.1515/pac-2017-0111)