Preparation and characterization of a new open‐tubular capillary column for enantioseparation by capillary electrochromatography

Abstract

In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with opentubular (OT) column, in this study, a new OT-CEC, coated with cationic cyclodextrin (1-allylimidazolium-β-cyclodextrin [AI-β-CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI-β-CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI-β-CD-coated column were optimized with the orthogonal experiment design L 9 (3 4 ). The column prepared was characterized by scanning electron microscopy (SEM) and elemental analysis (EA). The results showed that the thickness of stationary phase in the inner surface of the AI-β-CD-coated columns was about 0.2 to 0.5 μm. The AI-β-CD content in stationary phase based on the EA was approximately 2.77 mmol·m −2 . The AI-β-CD-coated columns could separate all 14 chiral compounds (histidine, lysine, arginine, glutamate, aspartic acid, cysteine, serine, valine, isoleucine, phenylalanine, salbutamol, atenolol, ibuprofen, and napropamide) successfully in the study and exhibit excellent reproducibility and stability. We propose that the column, coated with AI-β-CD, has a great potential for enantioseparation in OT-CEC.

β‐Cyclodextrin‐modified covalent organic framework as chiral stationary phase for the separation of amino acids and β‐blockers by capillary electrochromatography

“…With the increase of buffer solution pH, the amount of Si–OH dissociation and zeta potential increase, which led to the increase of EOF 47 . The EOF of MDI‐β‐CD‐modified COF‐coated OT column was smaller than that of the bare capillary column owing to the blocking of silanol 48 . It may be that the formation of EOF in MDI‐β‐CD‐modified COF‐coated OT column was mainly attributed to the dissociation of –NH 3 + on the surface of MDI‐β‐CD‐modified COF.…”

“…All of them were completely separated with separation factors ( α ) > 1.05 (Table 1). 48 However, labetalol contains two chiral centers, and four stereoisomers should have been separated. But according to the separation of other β‐blockers in Figure 6, only the hydroxyl chiral center was separated, and the carbon chiral center was not separated in labetalol.…”

“…47 The EOF of MDI-β-CD-modified COF-coated OT column was smaller than that of the bare capillary column owing to the blocking of silanol. 48 analytes and stationary phase. It was the reason that the EOF of MDI-β-CD-modified COF-coated OT column was stable enough to promote the applications on CEC mode.…”

A covalent organic framework for chiral capillary electrochromatography using a cyclodextrin mobile phase additive

“…30 Meanwhile, molecular stereo configuration affected the resolution of chiral enantiomers. 31 For example, fipronil have two aromatic rings, which may fit better in the CD cavity; the presence of hydroxyl or carbonyl groups in histidine can enhance the hydrogen bond interaction between hydroxyl groups of CD and histidine. 32 The results showed that all the analytes could be rapidly separated from the baseline under the optimized conditions of Method 2 with a resolution > 1.5 and a separation factor (α) > 1.05 (Table 2).…”

Recent developments of monolithic and open‐tubular capillary electrochromatography (2017–2019)

“…The β‐CD and derivatives have attracted extensive attentions and been used as the most popular chiral selectors in CEC , because they have the advantages of inexpensive, providing a fast equilibration of the CD‐solute complex, high efficiency, and a better peak symmetry . Guo et al.…”