Migration behavior of alkylphenols, bisphenol A and bisphenol S studied bycapillary electrophoresis using sulfated beta-cyclodextrin

An application of capillary electrophoresis (CE) using sulfated beta -cyclo dextrin (SCD) has been investigated for separating alkylphenols with differ ent chain lengths, as well as bisphenol A and bisphenol S. In the absence o f SCD in running buffer, all the phenols migrated at the same velocity as t he electroosmotic now (EOF), whereas the addition of SCD effectively led to the baseline separation of alkylphenols on the basis of the difference in the abilities to bind into the hydrophobic cavity of CD. The host-guest bin ding constants between analyte phenols and SCD were evaluated from Benesi-H ildebrand plots of the data obtained by two independent methods, CE and UV- visible measurements, demonstrating that the greater the hydrophobicity of the phenols, the larger the binding constants. The effects of organic solve nts on the resolution for alkylphenols and bisphenols were also examined. T his system using SCD was effective for the separation of 4-octylphenol and 4-nonylphenol isomers having longer alkyl chains.