Effect of the mobile phase on solute retention in liquid-solid chromatography

Abstract

Utilizing retention data estimated by HPTLC on silica and activity coefficients in the non-aqueous mobile phase determined on the basis of saturation solubility of solutes, the effect of the mobile phase on retention of a set of structurally different solutes was studied. A quadratic relationship between the logarithm of retention factors or activity coefficients and the volume fraction of ethyl acetate in heptane-ethyl acetate solution was observed, suggesting a common retention mechanism in liquid chromatography. The retention and/or relative retention of a solute was affected by both the mobile and the stationary phase. The magnitude of these effects depended merely on the molecular structure of a solute.