That value of pH in an aqueous phase at which the distribution ratio is unity at equilibrium. 50% of the solute is extracted
() only when the phase ratio is unity.
Source:
PAC, 1993, 65, 2373
(Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993))
on page 2385
) only when the phase ratio is unity.