Reversed-phase retention behaviour of Dns-amides as a function of eluent composition and molecular structrure in ethanol—water and methanol—water

Abstract

The reversed-phase liquid chromatographic retention of eighteen Dns-amides in ethanol—water and methanol—water was investigated. A high correlation was obtained when the volume fractions, ϕ, that produce the same retention in ethanol—water and methanol—water were plotted against each other. The same retention is obtained using a 0.1–0.2 higher volume fraction of methanol than ethanol in water. The molecular connectivity indices, χ, to sixth order were corrrelated with the log k′ values at various eluent compositions. The same parameters were chosen as the best descriptors of retention in the two eluents. Retention can be predicted with great accuracy and the best descriptors of retention are the zero valence level, oχ v , and the first valence level, 1χ v , indices.