Analytical Sciences

Migration Behavior of Alkylphenols, Bisphenol A and Bisphenol S Studied by Capillary Electrophoresis Using Sulfated beta-Cyclodextrin

Masanobu MORI,* Hisako NARAOKA,* Hirohito TSUE,* Tatsuya MOROZUMI,** Takashi KANETA,*** and Shunitz TANAKA* 

*Division of Material Science, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan
**Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
***Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan

An application of capillary electrophoresis (CE) using sulfated beta-cyclodextrin (SCD) has been investigated for separating alkylphenols with different chain lengths, as well as bisphenol A and bisphenol S. In the absence of SCD in running buffer, all the phenols migrated at the same velocity as the electroosmotic flow (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 binding constants between analyte phenols and SCD were evaluated from Benesi-Hildebrand 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 solvents on the resolution for alkylphenols and bisphenols were also examined. This system using SCD was effective for the separation of 4-octylphenol and 4-nonylphenol isomers having longer alkyl chains.

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