Non-aqueous capillary zone electrophoresis using polyethylene glycol as a matrix agent

Abstract

Non-aqueous capillary zone electrophoresis in acetonitrile containing polyethylene glycol as a matrix agent was investigated. Separation of benzoate anions as model samples were optimized by a control of the concentration and the selection of the chain length of polyethylene glycol. Base line resolution was attained in the presence of 15% (w/v) polyethylene glycol 4000 for the benzoates used. In acetonitrile, polyethylene glycol works as a hydrogen-bonding donor and acceptor; the terminal hydroxyl groups serve as a donor toward the dissociated carboxyl groups of the benzoates, while the ether oxygen atoms serve as an acceptor toward the hydrogen-donating substituents of the benzoates. This property of polyethylene glycol is in marked contrast with that observed in aqueous phase, where polyethylene glycol works predominantly as just a hydrogen acceptor. Quantitative analysis of the interaction is presented.