Min Zi

(R)‐N,N,N‐Trimethyl‐2‐Aminobutanol‐Bis(Trifluoromethane‐Sulfon)Imidate Chiral Ionic Liquid Used as Chiral Selector in HPCE, HPLC, and CGC

Abstract In this work, the (R)‐N,N,N‐trimethyl‐2‐aminobutanol‐bis(trifluoromethanesulfon)imidate chiral ionic liquid was first used in chromatography and exhibited a excellent chiral recognition ability in high performance capillary electrophoresis (HPCE), high performance liquid chromatography (HPLC), and capillary gas chromatography (CGC), which also showed for the first time that chrial ionic liquid was an effective chiral selector in HPCE and HPLC. The compounds that have been separated using this chiral ionic liquid at least included alcohol, amine, acid, and amino acid, et al. enantiomers. As the chiral ionic liquid can be easily synthesized from relatively inexpensive materials, it should have a great potentiality for chiral separation in chromatographic science.

Novel inorganic mesoporous material with chiral nematic structure derived from nanocrystalline cellulose for high-resolution gas chromatographic separations.

Chiral nematic mesoporous silica (CNMS) has attracted widespread attention due to some unique features, such as its nematic structure, chirality, large pore size, high temperature resistance, low cost, and ease of preparation. We first reported the use of CNMS as a stationary phase for capillary gas chromatography (GC). The CNMS-coated capillary column not only gives good selectivity for the separation of linear alkanes, aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and isomers but also offers excellent enantioselectivity for chiral compounds. Compared with enantioseparations on commercial β-DEX 120 and Chirasil-l-Val columns, a CNMS-coated capillary column offers excellent enantioselectivity, chiral recognition complementarity, and the separation of analytes within short elution times. It can also be potentially applied in high-temperature GC at more than 350 °C. This work indicates that CNMS could soon become very attractive for separations.

Versatile two-phase solvent system for alkaloid separation by high-speed counter-current chromatography.

In order to find a versatile high speed counter-current chromatography solvent system that can be used as a general prefractionation system for most alkaloids, the crude extracts of five Chinese traditional medicinal herbs, Cortex phellodendri, Semen strychni, green tea, Sophora flavescens ait, and Datura mete L. were resolved. All separations were performed only with a two-phase system composed of CHCl3-CH3OH-water (4:3:2). The water had different acidities controlled by adding NaH2PO4 or HCl to each sample. The fractionated components were identified by thin-layer chromatography, which confirmed this solvent system was versatile and very useful for the separation of alkaloids.

Preparative Enantioseparation of dl‐α‐Methylbenzylamine by High-Speed Countercurrent Chromatography using l‐(+)‐Tartaric Acid as Chiral Selector

Abstract Enantiomers of dl‐alpha‐methylbenzylamine were separated by high-speed countercurrent chromatography using l‐(+)‐tartaric acid as a chiral selector. The two phases system composed of chloroform:methanol:water=4:3:1 was chosen, which contained 278 mmol/L of chiral selector in the upper phase. The maximum of sample in a one time injection can be up to 120 mg. The enantiomers separated were identified by TLC and chiral HPLC, which confirmed that the method was very feasible for chiral preparative separation. This is the first report that l‐(+)‐tartaric acid was used as a chiral selector in the HSCCC.

VERSATILE TWO-PHASE SOLVENT SYSTEM FOR ANTHRAQUINONE PREFRACTIONATION BY HIGH SPEED COUNTERCURRENT CHROMATOGRAPHY

In order to find a high-speed countercurrent chromatography solvent system that can be used as a general prefractionation step for anthraquinone, the crude extracts of five traditional Chinese medicines, Radix rubiae, Rhizoma polygoni cuspidati, Semen cassiae, Radix et rhizoma rhei, and Aloe were separated with a two-phase system composed of CHCl3:CH3OH:H2O = 4:x:2 in which x was between 3 and 4 for different samples. The fractionated components were identified on TLC. This solvent system gave a good separation in most of the anthraquinones.

VERSATILE TWO-PHASE SOLVENT SYSTEM FOR FLAVONOID PREFRACTIONATION BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY

High-speed countercurrent chromatography was used for the prefractionation of flavonoids from the crude extracts of Pericarpium citri reticulatae, Radix puerariae, Radix glycyrrhizae, Radix scutellariae, and Flos genkwa. All separations were performed only with a two-phase system composed of CHCl3 : CH3OH :H2O=4 : x : 2. The x was changed for each sample between 2.5∼4.5. The fractionated components were identified by thin-layer chromatography, which confirmed this solvent system was versatile and very useful for prefractionation of flavonoids.

Separation of the cyclopeptide heterophyllin B by high-speed countercurrent chromatography and its application as a new stationary phase for capillary gas chromatography

ABSTRACT From the root of Pseudostellaria heterophylla a cyclopeptide, heterophyllin B, was isolated by high-speed countercurrent chromatography. Fused-silica capillary columns containing heterophyllin B as a main stationary phase component were prepared. The chromatographic selectivity of heterophyllin B showed toward aromatics, electron attracting compounds and amino acid.

Determination of Enantiomeric Excess by Solid-Phase Extraction Using a Chiral Metal-Organic Framework as Sorbent

Metal-organic frameworks (MOFs) have recently attracted considerable attention because of their fascinating structures and intriguing potential applications in diverse areas. In this study, we developed a novel method for determination of enantiomeric excess (ee) of (±)-1,1′-bi-2-naphthol by solid-phase extraction (SPE) using a chiral MOF, [Co(l-tyr)]n(l-tyrCo), as sorbent. After optimization of the experimental conditions, a good linear relationship between the ee and the absorbance of the eluate (R2 = 0.9984) was obtained and the standard curve was established at the concentration of 3 mmol L−1. The ee values of (±)-1,1′-bi-2-naphthol samples can be rapidly calculated using the standard curve after determination of the absorbance of the eluate. The method showed good accuracy, with an average error of 2.26%, and is promising for ee analysis.

A highly ordered chiral inorganic mesoporous material used as stationary phase for high-resolution gas chromatographic separations

A highly ordered chiral mesoporous silica-coated capillary column has been used for high-resolution gas chromatographic separations. The column has excellent selectivity, not only for the separation of isomers, polycyclic aromatic hydrocarbons, linear alkanes, long chain alkanes, Grobs test mixture and aromatic hydrocarbons, but also for the resolution of different classes of chiral compounds. Additionally, the column exhibits high column efficiency, excellent temperature resistance, and analysis times are short. This is the first report of a highly ordered chiral inorganic mesoporous silica used in separation science.

Direct thin-layer chromatographic enantioseparation of three aromatic dl-amino acids using vancomycin as the chiral selector

Chiral specificity is fundamental in pharmacology and chemical biology because stereochemistry plays a central role in controlling molecular recognition and interaction. The development of an effective method for analyzing pure enantiomers is very important. Currently, enantioseparation is typically performed either directly or indirectly by different chromatographic techniques. Considering the potential advantages of thin-layer chromatography (TLC) separation, that is, its simplicity and low cost, different chiral selectors have been used for TLC resolution of a variety of compounds into their enantiomers. Thus, various TLC enantioseparations have been developed for chiral compounds [1–3]. The current state of chiral separations by TLC via direct approach has been reviewed [4].