CHROMATOGRAPHY, Vol. 22 (2001), No. 3, pp. 187-194

Design for Valid “Surface” Property of Polymer-based Separation Media for Capillary Electrochromatography (CEC) : Correlation between Separation Selectivity, Retentivity and Generation of Electroosmotic Flow
Ken Hosoya*, Katsuo Takahashi, Takuya Kubo, Tohru Ikegami and Nobuo Tanaka
Department of Polymer Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan

Uniformly sized, polymer-based packing materials (particles) for high performance liquid chromatography (HPLC) and CEC were prepared through two different surface modification methods using methacrylic acid (MAA) as a functional monomer. The particles prepared using “mix method” afforded higher content of MAA, while “addition method” showed lower content of MAA, probably due to high solubility of MAA monomer into the dispersion continuous phase, water.
The particle prepared using addition method showed larger retention factor for hydrophobic solutes in HPLC mode, while the polymeric external surface layer derived from MAA resulted in slightly different separation selectivity especially at pH 10 with lower column efficiency. Although the content of MAA functionality was lower onto the particles prepared using addition method, it afforded higher electrooosmotic mobility compared with that by mix method in CEC mode. On the other hand, alkylbenzenes were separated with much larger retention factor on the particle prepared by addition method and column efficiency was found to be higher on the particle prepared by addition method, while in HPLC mode, the retention factor of alkylbenzenes was found to be smaller on the particle prepared by addition method probably due to higher surface hydrophilicity.
Keywords: electroosmotic flow, capillary electrochromatography, surface modification, separation selectivity

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