The use of characteristic volumes to measure cavity terms in reversed phase liquid chromatography

SummaryIn the correlation of reversed-phase liquid chromatography capacity factors through the equation, $$\log k' = log k'_0 + mV/100 + s\pi _2^* + b\beta _2 + a\alpha _2 $$ the use of McGowans characteristic volume, Vx, which can be trivially calculated, is entirely equivalent to the use of Leahy's computer-calculated intrinsic volumes, V1, for the cavity term mV/100. It is shown that for 209 gaseous, liquid, and solid solutes, the two sets of volumes are related through the equation, $$V_1 = 0.597 + 0.6823 V_x $$ with a standard deviation of only 1.24cm3 mol−1, and a correlation coefficient of 0.9988.