POLYALLYLAMINE-SUPPORTED PSEUDO-STATIONARY PHASES FOR ELECTROKINETIC CHROMATOGRAPHY - EFFECT OF ALKYL CHAIN-LENGTH OF THE PSEUDO-STATIONARYPHASE AND METHANOL CONTENT OF AQUEOUS BUFFER ON THE SEPARATION OF HYDROPHOBIC COMPOUNDS

Polymeric pseudo-stationary phases having alkyl (C-8-C-16) and carboxy late groups were prepared from commercially available polyallylamine ( PAA). PAA was first alkylated with an alkyl bromide, then reacted with methyl acrylate, followed by the hydrolysis of the ester functionalit y. The PAA-supported pseudo-stationary phases, especially those with l ong alkyl chains, provided high efficiencies for alkyl phenyl ketones and polynuclear aromatic hydrocarbons in a wide range of buffer-methan ol mixtures. Migration times of the hydrophobic compounds, limited by the migration time of the carrier (t(c)) at low methanol content, show ed a large increase at 40-60% methanol, and decreased due to the decre ase in k' values at higher methanol content where large t(c) values we re observed. The expansion of the migration time window occurred at a higher methanol content with the pseudo-stationary phase with the long er alkyl groups. Difference in the effect of methanol addition on the behavior of PAA derivatives with different alkyl groups can be attribu ted to the structural change of the polymeric pseudo-stationary phase resulting in the greater electrophoretic mobility relative to electroo smotic flow, and in turn large t(c) values. Simple preparation of the PAA-supported pseudo-stationary phase and the high efficiency will mak e electrokinetic chromatography using polymeric pseudo-stationary phas es a promising tool for the separation of a wide of compounds includin g very hydrophobic polynuclear aromatic hydrocarbons in simple water-m ethanol mixtures. (C) Elsevier Science B.V.