A comparative study of the gas chromatographic behavior of liquid crystals and polyester stationary phases using paraffinic hydrocarbons as standards

Abstract

AbstractTwo new categories of stationary phase have been studied: liquid crystals and polyesters. The liquid crystals were p,p′‐azoxyphenetol, p(n‐hexyloxy)phenyl‐p′‐methoxy benzoate, and p‐pentyloxy‐p′‐ethoxyazoxybenzene; and the polyester phases 1,4‐butanediol succinate (LAC‐860), ethylene glycol succinate (LAC‐886), diethylene glycol succinate (LAC‐738), diethylene glycol adipate (LAC‐296), and neopentyl glycol adipate (LAC‐769).Abnormal chromatographic behavior, has been observed: an increase in specific retention volumes and an improvement in the separation of normal, branched, and cycloparaffins, depending on their structures, at high temperatures within a specified range. This phenomenon is the opposite of the behavior of traditional stationary phases. From the chromatograms obtained, plots of log v against 1/T, and differential thermal analysis it is concluded that this abnormal behavior may be attributed to the penetration of solutes through the ordered structure of the mesophase and the rod‐like molecules of the polyesters. Furthermore, the chromatographic behavior of some of the polyester (LAC‐series) stationary phases in respect of temperature changes is similar to that of the nematic mesophases.