A simple molecular model of adsorption chromatography - VIII. Solvent composition effects in thin-layer chromatography of aromatic nitro compounds in (cyclohexane + polar solvent) - Silica type systems

Abstract

The relationship between the RM values of a number of aromatic nitro compounds and the composition of the solvent (moving phase) is interpreted in terms of an adsorption model. In accordance with this model, linear RM vs. log XS plots were obtained (XS is the mole fraction of the polar solvent) in wide composition ranges, the slopes of the plots being related to the molecular mechanism of adsorption and thus to the molecular structure of the chromatographed solute. The slopes indicate one-point attachment of the samples with one polar group and predominant two-point attachment of the samples with two or more polar groups (-NO2, -NH2, -OH). As in the case of the systems investigated in the previous papers of this series, the RM vs. log XS plots tend to spread fanwise with dilution of the polar solvent (improved selectivity). © 1975 Friedr. Vieweg & Sohn, Verlagsgesellschaft mbH.