When a two-phase system comprising an organic solution of any of various interfacially active neutral metal chelates in contact with an appropriate buffered aqueous phase is vigorously agitated, a reversible decrease in the organic phase concentration of the chelate is observed. This decrease gives rise to a shift in the pH(1/2) value of the metal ion (i.e., the pH corresponding to 50% extraction) from that observed in the corresponding unstirred system. The magnitude of this shift is shown to vary with the distribution constant of the chelate, the interfacial area generated upon stirring, and the organic solvent. In systems in which a pair of extractable metal chelates differing in interfacial activity is present, the shifts in pH(1/2) are shown to alter the apparent selectivity of the chelating extractant and to enhance the separation of the metal ions.