distribution

https://doi.org/10.1351/goldbook.D01811
The apportionment of a solute between two phases. The term partition or extraction may also be used in this sense where appropriate.
Source:
PAC, 1993, 65, 2373. 'Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)' on page 2377 (https://doi.org/10.1351/pac199365112373)