Capillary zone electrophoresis of basic proteins with chitosan as a capillary modifier

Abstract

Two new approaches based on the use of chitosan, a cationic natural polymer, have been developed for free solution capillary electrophoretic analysis of basic proteins. In the first method, chitosan was employed as a buffer additive in untreated fused-silica capillaries. The polymer interacts with the capillary surface, causes a reversal in the direction of the electroosmotic flow and reduces solute-wall interaction of basic proteins at pH values below their isoelectric points. High efficiencies (≥ 400000 theoretical plates/m) can be attained for most of the basic model proteins investigated in the pH range 3.0-5.5, except for lysozyme. Chitosan was also used as a capillary modifying reagent. Efficiencies obtained using the chitosan-modified capillary were generally lower than those with chitosan as a buffer additive. However, improvement in peak shape was obtained for lysozyme. In both cases, good migration time reproducibilities (R.S.D. < 1%) were obtained.