Electromigration behavior of a mixture of chitosan oligomers at different concentrations.

In this study, the effect of the concentration of a chitosan oligomer mixture on its electrophoretic behavior was studied as a function of pH and ionic strength added. It was shown that the concentration has a significant effect on the average electrophoretic mobility of the chitosan oligomer mixture and on isoelectric point. At a concentration of 3%, the ionic strength added did not show any effect on the electromigration behavior of the chitosan oligomer mixture. By decreasing the concentration of the chitosan oligomer mixture, ionic strength showed a significant effect on the average electrophoretic mobility but not on the isoelectric point. The highest shift of the isoelectric point was recorded in water at 0.003% concentration of the oligomer mixture. Under these conditions, the isoelectric point was at pH 5 whereas it was at pH 8 at 3% concentration of chitosan oligomer mixture. Electrophoretic measurements were also taken in water/ethanol aqueous medium. By adding ethanol to the medium, the average electrophoretic mobility decreased. This would have been caused by the increase in viscosity of the medium. Increasing ethanol ratio in the running medium, the isoelectric point moved from pH 5 in water up to pH 6-8 dependently on chitosan oligomer mixture concentration and ethanol content of the medium.