Preparation and characterization of monolithic columns for capillary electrochromatography with weak electroosmotic flow

Monolithic columns of capillary electrochromatography (CEC) with weak electroosmotic flow (EOF) have been prepared by in situ polymerization of butyl methacrylate and ethylene dimethacrylate, without any charged groups in the reaction mixture. The reproducibility of such columns has been proved good no matter whether they are prepared in the same batch or in different batches. In the case of BMA-EDMA monoliths, besides the traditional ternary mixture - 1-propanol, 1,4-butanediol, and water, binary porogenic solvents with only alcohols have also been adopted. Compared with ternary porogenic solvents, the design with binary ones allows for fine control of the pore diameter and the formation of the specific surface of the monolithic polymers. The composition of porogenic reagents has also been shown to have an effect on EOF in the column systems. In addition, the Joule heat effect in such columns has been studied by varying the inner diameter of columns. Through the separation of acidic compounds, monolithic columns with low EOF have shown potential in the analysis of charged samples.