Separation and on-line concentration of bisphenol A and three alkylphenols were investigated by micellar electrokinetic chromatography with the anionic surfactant, sodium dodecyl sulfate. The separation conditions were optimized by the simultaneous addition of the organic solvent and cyclodextrin to the running solution. The separation of hydrophobic analytes and 4-nonylphenol isomers was improved by the addition of 10% methanol and 5 mM beta-cyclodextrin to the running solution. When the sweeping with the running solution was used as the on-line concentration procedure, 69-, 48-, 55- and 41-fold increases in detection sensitivity were obtained for bisphenol A, 4-tert.-butylphenol and 4-(1,1,3,3-tetramethylbutyl)phenol, and the second peak of 4-nonylphenol isomers, respectively. The detection limits were 0.0071, 0.0065, 0.021 and 0.055 mg/l, respectively. These results were better than those with the cationic surfactant, tetradecyltrimethylammonium bromide.
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