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

Cyclodextrin-modified micellar electrokinetic chromatography was applied to the separation of benzo[a]pyrene and 12 positional isomers of monohydroxyb enzo[a]pyrenes using gamma-cyclodextrin together with sodium dodecyl sulfat e. The optimum running conditions were found to be 20 mM phosphate-5 mM bor ate buffer (pH 8.5) containing 20 mM gamma-cyclodextrin and 50 mM sodium do decyl sulfate with an effective voltage of 12 kV at 20 degrees C. Octanol-w ater distribution coefficients of the compounds in the presence of gamma-cy clodextrin were measured as an index of the association constants for compl exes of gamma-cyclodextrin with these compounds. The migration time of the analytes correlated well with their distribution coefficients, suggesting t hat their migration order could be correctly predicted on the basis of calc ulations of host-guest interaction energies. The relationship between the m igration order and the structures of monohydroxybenzo[a]pyrene isomers is d iscussed.