The process of transferring a substance from any matrix to an appropriate liquid phase. If the substance is initially present as a solute in an immiscible liquid phase the process is synonymous with liquid-liquid extraction
If the extractable material is present in a solid (such as a crushed mineral or an ore) the term leaching may be more appropriate. The extractable material may also be a liquid entrapped within or adsorbed on a solid phase.
Common usage has established this term as a synonym for liquid-liquid distribution. This is acceptable provided that no danger of confusion with extraction from solid phases exists in a given context.
PAC, 1993, 65, 2373
(Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993))
on page 2379
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook