Micellar electrokinetic chromatography of monohydroxybenzo[a]pyrene positional isomers using γ-cyclodextrin

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Cyclodextrin-modified micellar electrokinetic chromatography was applied to the separation of benzo[a]pyrene and 12 positional isomers of monohydroxybenzo[a]pyrenes using γ-cyclodextrin together with sodium dodecyl sulfate. The optimum running conditions were found to be 20 mM phosphate–5 mM borate buffer (pH 8.5) containing 20 mM γ-cyclodextrin and 50 mM sodium dodecyl sulfate with an effective voltage of 12 kV at 20 °C. Octanol–water distribution coefficients of the compounds in the presence of γ-cyclodextrin were measured as an index of the association constants for complexes of γ-cyclodextrin with these compounds. The migration time of the analytes correlated well with their distribution coefficients, suggesting that their migration order could be correctly predicted on the basis of calculations of host–guest interaction energies. The relationship between the migration order and the structures of monohydroxybenzo[a]pyrene isomers is discussed.