RETENTION BEHAVIOR OF TRIBUTYLPHENOL ETHYLENE-OXIDE OLIGOMERS ON AN ALUMINA HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC COLUMN

The retention behaviour of tributylphenol ethylene oxide oligomer surf actants was studied on an alumina HPLC column using ethyl acetate-n-he xane mixtures as eluents. The surfactants contained various numbers of ethylene oxide groups per molecule and tributylphenol isomers as hydr ophobic moieties. The column separated the surfactants according to th e length of the ethylene oxide chain and the position of butyl substit uents in one run, demonstrating the good separation power of alumina. A significant linear correlation was found between the logarithm of th e capacity factor of each surfactant and the concentration of ethyl ac etate 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 ef fect than the position of the butyl substituents in the tributylphenol moiety on the retention.