Facile Liquid Chromatographic Separation of Positional Isomers with a γ-Cyclodextrin Bonded Phase Column

Facile isocratic liquid chromatographic separation of positional isomers of substituted anilines is demonstrated using a γ-cyclodextrin (γ-CD) bonded phase column. It is found that normal phase separation is more effective than reversed-phase separation for these compounds. The effect of mobile phase composition on the retention of several substituted anilines is also examined. A minimum value of the capacity factor (k') for each compound is seen at a mobile phase composition of 60% 2-propanol in water and a rationalization of this unusual observation is proposed. The effect of cavity size of cyclodextrins on the retention of solutes is also discussed.