Separation of hydrophobic solutes by nonaqueous capillary electrophoresis through dipolar and charge-transfer interactions with pyrylium salts

In this study, the use of pyrylium salts for the separation of uncharged hydrophobic solutes in nonaqueous capillary electrophoresis (NACE) is examined. In an aprotic solvent such as acetonitrile, large polarizable compounds selectively interact with planar organic cations, thereby facilitating the analysis of solutes that have low solubilities in aqueous or mixed solvents. Presented in this article are the separations of polycyclic aromatic hydrocarbons (PAHs) that were achieved through dipolar and charge-transfer interactions with various substituted pyrylium cations. It was found that the number of rings contained in the PAH molecule, the presence of functional groups on the molecule, the concentration of the pyrylium cation, and the number of phenyl substituents on the pyrylium ring affected the electrophoretic mobility of the solute–cation complex.