phase ratio, r in liquid-liquid distribution, in chromatography

https://dx.doi.org/10.1351/goldbook.P04532
The ratio of the quantity of the solvent to that of the other phase.
Notes:
  1. Unless otherwise specified the phase ratio refers to the phase volume ratio.
  2. If other aspects of the phase ratio are employed viz. phase mass ratio, phase flow ratio, these should be specified.
Source:
PAC, 1993, 65, 2373 (Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)) on page 2385