Effects of electrokinetic chromatography conditions on the structure and properties of polyallylamine-supported pseudo-stationary phase A study by dynamic light scattering

The hydrophobic selectivity and electrophoretic mobility of polymeric pseudo-stationary phases supported by polyallylamine (PAA) were found to be affected by the degree of alkylation of PAA, the organic solvent content of the separation medium, and also by the concentration of the pseudo-stationary phase. The results obtained with dynamic light scattering, fluorescence spectroscopy, viscosity measurement and electrokinetic chromatography indicate that the PAA-supported pseudo-stationary phases assume swollen structures to expose more ionic groups to the aqueous medium at a lower concentration and at a higher organic solvent content, leading to the lower hydrophobic property and the greater electrophoretic mobility, which in turn result in the wider migration time window. Inadequate solvation of alkyl groups causes intermolecular aggregation of the polymeric carriers in aqueous buffer solutions, especially at high carrier concentrations. Dynamic light scattering measurement was shown to be particularly useful to elucidate the conformational change of the polymeric pseudo-stationary phase under various conditions. (C) 1999 Elsevier Science B.V. All rights reserved.