[Preparation of strong cation-exchange monolithic column and its application in polypeptide separation by capillary...

A strong cation-exchange monolithic column was prepared by polymerization inside the fused-silica capillary. The solution consisted of acrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid as functional monomers, N,N'-methylenebisacrylamide as a cross-linking agent, dimethyl suiphoxide and dodecanol, 1 , 4-butanediol as organic porogenic solvents and azobisisobutyronitrile as a suitable initiator. The effects of the applied voltage, concentrations of organic modifier and salt solution, pH value on the electroosmotic flow were investigated. The experimental results showed that there existed a good linear relationship between the applied voltage and electroosmotic flow with a correlation coefficient of 0.9981; When the concentration of organic modifier (acetonitrile, ACN) was less than 70%, the swelling degree of stationary phase played a main role and the electroosmotic flow was decreased abnormally with the increase of ACN concentration; The electroosmotic flow was decreased with the increase of the concentration of phosphate. When the pH value was in the range of 3-9, it did not exert a significant change in electroosmotic flow. These results were consistent with the theoretical role. At the same time, five peptides were separated successfully under the optimal experimental conditions on the monolithic column for capillary electrochromatography. The column has obvious advantages in polypeptide separation and will be favorable for the protein investigation.