双阳离子型离子液体和十八烷基修饰的混合模式硅胶固定相的制备及色谱性能

通过分步键合反应制备了一种咪唑基双阳离子型离子液体和十八烷基共同修饰的混合模式硅胶色谱固定相(Sil-C18-IL-C4); 采用元素分析和红外光谱对其进行了表征. 分别评价了该固定相在反相色谱模式(RPLC)、 亲水色谱模式(HILIC)和RPLC/HILIC混合色谱模式下的色谱分离性能, 并在HILIC模式下对6种碱基核苷类化合物进行分离, 考察了流动相中有机相体积分数和水相中甲酸铵浓度对分离效果的影响. 此外, 还考察了该固定相的分离重复性. 制备的Sil-C18-IL-C4固定相的元素分析结果表明, 氮元素含量为1.65%, 碳元素含量为11.16%, 氢元素含量为2.44%. 该固定相的红外光谱中, 2928和2856 cm^?1处出现了—CH的不对称和对称伸缩振动峰, 1440 和660 cm^?1处出现了咪唑环上C=C的伸缩振动峰和C=N的弯曲振动峰, 说明十八烷基和1,5-双(咪唑-1-基)戊烷均已接枝到硅胶表面. 色谱性能评价结果表明, Sil-C18-IL-C4固定相可表现出反相色谱模式和亲水色谱模式分离性能, 对6种碱基核苷类物质能够实现完全分离, 而且在一定的色谱条件下可以在单根色谱柱单次运行中实现RPLC/HILIC混合模式色谱分离, 对于处理复杂样品中的碱基核苷类化合物等亲水物质具有良好的应用潜能.

Preparation and Chromatographic Performance of Mixed-mode Silica Stationary Phase Modified by Double Cationic Ionic Liquid and Octadecyl Group

In this paper, a mixed-mode silica chromatography stationary phase（Sil-C18-IL-C4） modified by imidazole-based double cationic ionic liquid and octadecyl group was prepared by a step-by-step bonding reaction. The stationary phase was characterized by elemental analysis and infrared spectroscopy. The chromatographic separation performance of the stationary phase in reversed-phase mode（RPLC）, hydrophilic mode（HILIC） and RPLC/HILIC mixed-mode were evaluated, respectively, and 6 base nucleosides were separated in HILIC mode. The influence of the volume fraction of the organic phase and the concentration of ammonium formate in the aqueous phase on the separation effect was also investigated. In addition, the repeatability of stationary phase separation was investigated. Elemental analysis and characterization of the prepared Sil-C18-IL-C4 stationary phase show that the nitrogen content was 1.65%, the carbon content was 11.16%, and the hydrogen content was 2.44%. In the characterization results of infrared spectroscopy, the asymmetric and symmetric stretching vibration peaks of —CH appeared at 2928 and 2856 cm^?1, and the stretching of C=C on the imidazole ring appeared at 1440 and 660 cm^?1. The vibration peaks and the bending vibration peaks of C=N indicate that both octadecyl and 1,5-bis（imidazol-1-yl）pentane were grafted onto the silica surface. The chromatographic performance evaluation results showed that the Sil-C18-IL-C4 mixed-mode silica stationary phase could simultaneously exhibit reversed-phase and hydrophilic-interaction chromatogra-phic separation performance, and could completely separate 6 kinds of base nucleosides. Moreover, under certain chromatographic conditions, the RPLC/HILIC mixed separation mode can be realized in a single run of a single chromatographic column. It has good application potential for solving hydrophilic substances such as base nucleosides in complex samples.