Influence of intramolecular interactions on chromatographic behaviour of arylaliphatic acids : I. Comparison of reversed-phase thin-layer and high-performance liquid chromatography

Abstract

Series of arylacetic acids were subjected both to reversed-phase thin-layer chromatography and to high-performance liquid chromatography using chemically bonded packing materials. In addition to the reference series of arylacetic acids, the dialkoxy and phenylalkoxy derivatives were also studied as their lipophilicities were influenced by intramolecular interactions. The influence of various stationary phases upon changes in lipophilicity of the dialkoxy and phenylalkoxy derivatives was studied through relationships between π and the retention indices ( R M or log k′). It was found that when an aqueous mobile phase containing an organic solvent (50% acetone or 60% methanol) was used, the changes in lipophilicity of the dialkoxy and phenylalkoxy derivatives corresponded to the changes in lipophilicity measured in the reference system n-octanol—water. Extrapolation of retention indices to pure water was not advantageous, and negatively influenced the calculation of the π parameters for the dialkoxy and phenylalkoxy derivatives from the corresponding retention indices.