phase ratio, β in chromatography

The ratio of the volume of the mobile phase to that of the stationary phase in a column:

$β = V 0 V s$

In the case of open-tubular columns the geometric internal volume of the tube ( $V c$ ) is to be substituted for $V 0$ .

Source:

PAC, 1993, 65, 819 (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 833