Gao Lidi, Zhao Xuan, Qin Shili, Dong Qing, Hu Xingfang, Chu Hongtao
College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar, China.
Chirality. 2022 Mar;34(3):537-549. doi: 10.1002/chir.23405. Epub 2022 Jan 7.
Covalent organic frameworks (COFs) have been recognized as promising solid phases in capillary electrochromatography (CEC). Imine-based COF-coated open-tubular CEC column (COF TpBD-coated OT column) was prepared and characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectra, thermogravimetric analysis (TGA), nitrogen adsorption/desorption (Brunauer-Emmett-Teller [BET]), and scanning electron microscopy (SEM). The results showed that the column efficiency was up to 26,776 plate/m, and the thickness of stationary phase was about 6.00 μm for the column prepared under the optimal conditions. Enantioseparation of 15 kinds of the single chiral compounds (histidine, arginine, lysine, leucine, threonine, methionine, valine, aspartic acid and glutamic acid, fipronil, diclofop, imazamox, quizalofop-p, imazethapyr, and acephate) and 3 kinds of mixed amino acids racemaces (valine, methionine, and glutamic acid) were performed with three methods: capillary electrochromatography with COF TpBD-coated OT column (Method 1), CEC with COF TpBD-coated OT column as the separation channels, and capillary electrophoresis (CE) with HP-β-CD as the chiral mobile phase additive (Method 2) and CE with HP-β-CD as the chiral mobile phase additive (Method 3). Separation efficiency and chiral selectivity of Method 2 was best among the three methods. Under the optimal separation conditions of Method 2, all the enantiomers reached the baseline separation regardless of the single chiral compounds or the mixed amino acids. Relative standard deviation (RSDs) of the mean column efficiency for reproducibility and stability was in the range of 0.46-1.49%. This combination of CEC and CE has great potential for use in chiral separation.
共价有机框架（COFs）已被公认为是毛细管电色谱（CEC）中很有前景的固定相。制备了基于亚胺的COF涂层开管CEC柱（COF TpBD涂层OT柱），并通过X射线衍射（XRD）、傅里叶变换红外（FT-IR）光谱、热重分析（TGA）、氮吸附/脱附（Brunauer-Emmett-Teller [BET]）和扫描电子显微镜（SEM）对其进行了表征。结果表明，在最佳条件下制备的柱效高达26776板/米，固定相厚度约为6.00μm。采用三种方法对15种单一手性化合物（组氨酸、精氨酸、赖氨酸、亮氨酸、苏氨酸、蛋氨酸、缬氨酸、天冬氨酸和谷氨酸、氟虫腈、双氯芬酸、咪唑乙烟酸、精喹禾灵、咪唑乙烟酸和乙酰甲胺磷）和3种混合氨基酸外消旋体（缬氨酸、蛋氨酸和谷氨酸）进行了对映体分离：使用COF TpBD涂层OT柱的毛细管电色谱（方法1）、以COF TpBD涂层OT柱为分离通道的CEC以及以HP-β-CD为手性流动相添加剂的毛细管电泳（CE）（方法2）和以HP-β-CD为手性流动相添加剂的CE（方法3）。三种方法中，方法2的分离效率和手性选择性最佳。在方法2的最佳分离条件下，无论是单一手性化合物还是混合氨基酸，所有对映体均实现了基线分离。柱效均值的重现性和稳定性的相对标准偏差（RSDs）在0.46 - 1.49%范围内。这种CEC和CE的组合在手性分离方面具有很大的应用潜力。
