Molecular-shape selective high-performance liquid chromatography: Stabilization effect of polymer main chain by alternating copolymerization

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• 作者：Abul K. Mallik^a ; Hongdeng Qiu^a ; Tsuyoshi Sawada^a ; ^b ; Makoto Takafuji^a ; ^b ; Hirotaka Ihara^a ; ^b ; ^{ihara@kumamoto-u.ac.jp}
• 关键词：Reversed-phase chromatography ; Alternating copolymer ; Molecular shape-selectivity ; Carbonyl&ndash ; 蟺 interaction ; Polycyclic aromatic hydrocarbons ; Tocopherols ; Carotenoids
• 刊名：Journal of Chromatography A
• 出版年：2012
• 期刊代码：47_00219673
• 类别：ch
• 出版时间：6 April, 2012
• 卷：1232
• 期：Complete
• 页码：183-189
• 文件大小：798 K

摘要

This work aims to clarify that stabilization or increased rigidity of polymer main chains as an organic stationary phase can lead the selectivity enhancement in high-performance liquid chromatography (HPLC). For this purpose, the alternating copolymer of octadecyl acrylate (ODA) with a cyclic monomer (N-octadecylmaleimide, OMI) as a rigid segment was synthesized and compared with the ODA homopolymer. Both of the polymer-grafted silicas (Sil-poly(ODA-alt-OMI) and Sil-poly(ODA), respectively) were prepared by radical polymerization on 3-mercaptopropyltrimethoxysilane-modified silica. The characterizations were carried out by elemental analyses, diffuse reflectance infrared Fourier transform (DRIFT), and solid-state ¹³C cross-polarization magic angle spinning nuclear magnetic resonance (CP-MAS-NMR) spectroscopies. Chromatographic behaviors were evaluated by the retention studies of shape-constrained isomers of polycyclic aromatic hydrocarbons (PAHs), isomers of tocopherol and carotenoids. Higher molecular-linearity selectivity toward PAHs was obtained on Sil-poy(ODA-alt-OMI) regardless of temperature changes but at temperature below 40 掳C, Sil-poly(ODA) showed better planarity selectivity than that of Sil-poy(ODA-alt-OMI). As a result, the higher separation ability toward tocopherols and carotenoids was obtained on Sil-poy(ODA-alt-OMI). These results indicate that the stabilization in the polymer main chain by alternating copolymerization and the stabilization in the side chains by a disordered-to-ordered phase transition were effective to enhance the molecular-shape selectivity.