The ratio of the proportion of contaminant to product before treatment to the proportion after treatment. It is the reciprocal of the enrichment factor.
Source:
PAC, 1993, 65, 2373. 'Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)' on page 2381 (https://doi.org/10.1351/pac199365112373)