Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-3071, USA.
Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-3071, USA.
Talanta. 2018 Mar 1;179:632-640. doi: 10.1016/j.talanta.2017.11.062. Epub 2017 Dec 2.
This research article presents the preparation and characterization of monolithic capillary columns with incorporated bare fumed silica nanoparticles (FSNPs) and surface coated gluconamide FSNPs and their subsequent use in hydrophilic interaction capillary electrochromatography (HI-CEC) of small relatively polar solutes. The monolithic support was based on the in situ polymerization of glyceryl monomethacrylate (GMM) and ethylene glycol dimethacrylate (EDMA) yielding the poly(GMM-co-EDMA) monolith for the incorporation of bare and gluconamide-FNSPs. The poly(GMM-co-EDMA) monolith functioned as a true "support" for both types of polar FSNPs "stationary phases". In other words, monolithic capillary columns with "FSNPs stationary phases" were obtained in the sense that the contribution of the monolith proper to solute' retention was at its minimum. The gluconamide-FSNPs were obtained by reacting the FSNPs with the polar organosilane N-(3-triethoxysilylpropyl)gluconamide either by a pre- or on-column approach yielding p-gluconamide-FSNPs or o-gluconamide-FSNPs, respectively. While the p-gluconamide-FSNPs was coated by an oligosiloxane gluconamide layer as revealed by thermogravimetric analysis, the o-gluconamide-FSNPs are thought to be covered with a monomeric layer of gluconamide ligands as was manifested by the higher plate number obtained on the latter than on the former gluconamide-FSNPs incorporated monolithic columns. In the on-column modification process of FSNPs, the reaction was performed in a closed system whereby atmospheric water vapor are not available to cause the polymerization of the trifunctional organosilane N-(3-triethoxysilylpropyl)gluconamide. Also, the fact that the o-gluconamide-FSNPs incorporated monoliths were made from bare-FSNPs incorporated monoliths may indicate that the bare FSNPs were better dispersed into the monolithic matrix than the p-gluconamide-FSNPs, a condition that might have further contributed to the lower plate count obtained on p-gluconamide- than o-gluconamide-FSNPs incorporated monolithic columns. Overall, o-gluconamide-FSNPs stationary phases and to a lesser extent bare-FSNPs stationary phases proved useful in HI-CEC of small polar solutes, including DMF, formamide, thiourea, some phenols and nucleobases.
本文介绍了通过原位聚合制备和特性研究单分散整体毛细管柱，其中包含了裸露的气相二氧化硅纳米粒子（FSNPs）和表面涂覆的葡萄糖酰胺 FSNPs，并将其应用于小而相对极性溶质的亲水相互作用毛细管电色谱（HI-CEC）中。整体支撑物是基于甘油单甲基丙烯酸酯（GMM）和乙二醇二甲基丙烯酸酯（EDMA）的原位聚合，生成用于掺入裸露和葡萄糖酰胺 FSNPs 的聚（GMM-co-EDMA）整体。聚（GMM-co-EDMA）整体作为两种类型的极性 FSNPs“固定相”的真正“支撑物”。换句话说，通过在单分散整体毛细管柱中获得“FSNPs 固定相”，从而使单分散整体对溶质保留的贡献最小。通过与极性有机硅烷 N-（3-三乙氧基丙基）葡萄糖酰胺反应，分别以预柱或柱上方式获得 p-葡萄糖酰胺 FSNPs 或 o-葡萄糖酰胺 FSNPs，从而得到葡萄糖酰胺 FSNPs。虽然通过热重分析表明 p-葡萄糖酰胺 FSNPs 被低聚硅氧烷葡萄糖酰胺层覆盖，但认为 o-葡萄糖酰胺 FSNPs 被葡萄糖酰胺配体的单体层覆盖，因为在后一种 o-葡萄糖酰胺 FSNPs 掺入的整体柱上获得的板数高于前一种 p-葡萄糖酰胺 FSNPs 掺入的整体柱。在 FSNPs 的柱上修饰过程中，反应是在封闭系统中进行的，因此大气水蒸气无法引发三官能有机硅烷 N-（3-三乙氧基丙基）葡萄糖酰胺的聚合。此外，o-葡萄糖酰胺 FSNPs 掺入的整体柱是由裸露的 FSNPs 掺入的整体柱制成的这一事实可能表明，裸露的 FSNPs 比 p-葡萄糖酰胺 FSNPs 更好地分散在整体基质中，这种情况可能进一步导致在 p-葡萄糖酰胺-FSNPs 掺入的整体柱上获得的板数低于 o-葡萄糖酰胺-FSNPs 掺入的整体柱。总体而言，o-葡萄糖酰胺 FSNPs 固定相，在较小程度上，裸露的 FSNPs 固定相，在小而极性溶质的 HI-CEC 中证明是有用的，包括 DMF、甲酰胺、硫脲、一些酚类和碱基。
