Department of Applied Chemistry and Chemical Engineering, University of Dhaka, Dhaka 1000, Bangladesh.
Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto, Japan.
J Chromatogr A. 2018 Jun 22;1555:53-61. doi: 10.1016/j.chroma.2018.04.047. Epub 2018 Apr 23.
The synthesis of a new alternating copolymer-grafted silica phase is described for the separation of shape-constrained isomers of polycyclic aromatic hydrocarbons (PAHs) and tocopherols in reversed-phase high-performance liquid chromatography (RP-HPLC). Telomerization of the monomers (octadecyl acrylate and N-methylmaleimide) was carried out with a silane coupling agent; 3-mercaptopropyltrimethoxysilane (MPS), and the telomer (T) was grafted onto porous silica surface to prepare the alternating copolymer-grafted silica phase (Sil-alt-T). The new hybrid material was characterized by elemental analyses, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and solid-state C and Si cross-polarization magic-angle spinning (CP/MAS) NMR spectroscopy. The results of C CP/MAS NMR demonstrated that the alkyl chains of the grafted polymers in Sil-alt-T remained disordered, amorphous, and mobile represented by gauche conformational form. Separation abilities and molecular-shape selectivities of the prepared organic phase were evaluated by the separation of PAHs isomers and Standard Reference Material 869b, Column Selectivity Test Mixture for Liquid Chromatography, respectively and compared with commercially available octadecylsilylated silica (ODS) and C columns as well as previously reported alternating copolymer-based column. The effectiveness of this phase is also demonstrated by the separation of tocopherol isomers. Oriented functional groups along the polymer main chains and cavity formations are investigated to be the driving force for better separation with multiple-interactions with the solutes. One of the advantages of the Sil-alt-T phase to that of the previously reported phase is the synthesis of the telomer first and then immobilized onto silica surface. In this case, the telomer was characterized easily with simple spectroscopic techniques and the molecular mass and polydispersity index of the telomer were determined by size exclusion chromatography (SEC) before grafting onto silica surface. Moreover, both of the monomers were commercially available. Therefore, the technique of preparation was very facile and better separation was achieved with the Sil-alt-T phase compared to the ODS, C and other previously reported alternating copolymer-based columns.
本文描述了一种新的交替共聚物接枝硅胶相的合成方法，用于反相高效液相色谱（RP-HPLC）中分离多环芳烃（PAHs）和生育酚的形状受限异构体。单体（十八烷基丙烯酸酯和 N-甲基马来酰亚胺）与硅烷偶联剂 3-巯丙基三甲氧基硅烷（MPS）进行齐聚反应；齐聚物（T）接枝到多孔硅胶表面，制备交替共聚物接枝硅胶相（Sil-alt-T）。新的杂化材料通过元素分析、漫反射红外傅里叶变换（DRIFT）光谱和固态 C 和 Si 交叉极化魔角旋转（CP/MAS）NMR 光谱进行了表征。C CP/MAS NMR 的结果表明，Sil-alt-T 中接枝聚合物的烷基链保持无序、无定形和移动，表现为 gauche 构象形式。通过分离 PAHs 异构体和标准参考物质 869b（液相色谱柱选择性测试混合物），分别评估了制备的有机相的分离能力和分子形状选择性，并与市售的十八烷基硅烷化硅胶（ODS）和 C 柱以及之前报道的交替共聚物柱进行了比较。该相还通过生育酚异构体的分离证明了其有效性。沿聚合物主链的定向官能团和空腔的形成被认为是与溶质进行多种相互作用从而实现更好分离的驱动力。Sil-alt-T 相与之前报道的相相比的一个优势是首先合成齐聚物，然后将其固定在硅胶表面上。在这种情况下，齐聚物可以通过简单的光谱技术轻松表征，并且可以通过尺寸排阻色谱（SEC）在接枝到硅胶表面之前确定齐聚物的分子量和多分散指数。此外，两种单体均为市售产品。因此，与 ODS、C 和其他之前报道的基于交替共聚物的柱相比，该制备技术非常简单，Sil-alt-T 相实现了更好的分离。
