[Preparation of low electroosmotic flow monolithic capillary column and the investigation on its properties]

Monolithic columns of capillary electrochromatography (CEC) with low electroosmotic flow (EOF) have been prepared by in-situ polymerization of butylmethacrylate and ethylene dimethacrylate, without any charged groups existed in the reaction mixture. The good reproducibility of the columns has been proved no matter if they are prepared in the same or different batches. Besides the traditional ternary porogenic mixture of 1-propanol, 1,4-butanediol and water, a binary porogenic mixture with only alcohols has also been adopted. In comparing with the ternary porogenic mixture, the design of binary mixture allows fine control of pore diameter and the formation of specific surface of the monolithic polymers. The effects of composition and ratio of porogenic reagents on EOF of the column systems have also been shown. The pore properties and EOF of monolithic columns with different porogenic mixtures were investigated. The results of scanning-electron micrograph show that the continuous beds were quite different from each other, while the proportions of 1-propanol were the same under these two situations. In addition, the Joule heat effect of such columns has been studied by varying the inner diameter of capillary columns. The effect of length of capillary on the EOF was also studied. Under the conditions of high pH and high concentrations of organic solvents, low EOF was obtained to satisfy different needs from the diversified separation modes. Through the separation of acidic compounds, monolithic columns with low EOF have shown potentialities in the analysis of charged samples.