Retention behaviour of tributylphenol ethylene oxide oligomers on an alumina high-performance liquid chromatographic column

Abstract

The retention behaviour of tributylphenol ethylene oxide oligomer surfactants was studied on an alumina HPLC column using ethyl acetate- n-hexane mixtures as eluents. The surfactants contained various numbers of ethylene oxide groups per molecule and tributylphenol isomers as hydrophobic moieties. The column separated the surfactants according to the length of the ethylene oxide chain and the position of butyl substituents in one run, demonstrating the good separation power of alumina. A significant linear correlation was found between the logarithm of the capacity factor of each surfactant and the concentration of ethyl acetate in the eluent, but the dependence of the retention on the ethyl acetate concentration was low. Stepwise regression analysis indicated that the number of ethylene oxide groups per molecule has a greater effect than the position of the butyl substituents in the tributylphenol moiety on the retention.