Study of Chiral Ionic Liquid as Stationary Phases for GC

Due to the synthetic flexibility and special enantioselectivity, chiral ionic liquids (CILs) have heightened interest and an increasing number of CILs has been designed and utilized. In this work, CIL named l-1-butyl-3-(2-propionic-1-ether) imidazolium bromide ([BAlaIM]Br) derived from natural amino acids was synthesized, with chiral center at cation moiety. Chiral stationary phases for gas chromatography were then prepared by mixing the CIL with polymeric ionic liquid ([PSOMIM][NTf₂], homemade) at different ratios (4:1, 2:1, and 1:1). The column efficiency was measured to be about 3,200 plates m⁻¹ (8 m × 0.25 mm i.d.) when the content of [BAlaIM]Br was 50 % (mass percent) in the mixed stationary phase. All columns were coated via the static coating method using 0.30 % (w/v) of stationary phases dissolved in methanol. The results showed that the CIL contributed to the selectivity of stationary phase toward positional isomers dichlorobenzenes, methylnaphthalenes and pinenes, etc. Meanwhile, [BAlaIM]Br showed better selectivity for enantiomers such as carvones, citronellals, limonenes and camphors. The interactions between chiral selector and enantiomers were also discussed.

     

The Evolution of Chiral Stationary Phases for Liquid Chromatography

The development of effective chiral stationary phases (CSPs) and separation strategies for the liquid chromatographic (LC) resolution of enantiomers has been beneficial to many scientific disciplines. Over the last decade the number and type of CSPs has expanded tremendously. Not only have new classes of chiral selectors been introduced, but also many of the first CSPs have been changed and/or improved. The second or third generation of a CSP often can be different from the original. This can be confusing and intimidating to someone just entering the area of LC enantiomeric separations. Fortunately, all CSPs can be categorized in one or another of a few classes. There are generally one or two columns that can accomplish the majority of separations in each class. In this work we look at the different classes of CSPs and how they have expanded and changed over the last decade.     

Study of Anion Effects on Separation Phenomenon for the Vinyloctylimidazolium Based Ionic Liquid Polymer Stationary Phases in GC

Poly-vinyloctylimidazolium ionic liquid polymers with different counter ions (bromide, hexafluorophosphate and bis-trifluoromethanesulfonylimide) were directly coated in capillary fused silica tubing as the stationary phases for gas chromatography. The anion effects on the polymers were examined and discussed. The results suggest that the poly-vinyloctylimidazolium, bis-trifluoromethanesulfonylimide capillary column has the highest thermal stability and separation efficiency. Column-to-column reproducibility was also studied. The results indicate that anions significantly influence ionic liquid polymers which give them potential to extend the range of options for the stationary phases in gas chromatography.     

纤维素衍生物手性固定相用于高效液相色谱对映体分离

纤维素衍生物是目前高效液相色谱 (HPLC)中应用最为广泛的手性固定相之一 ,对各种类型的外消旋体都表现出了很高的对映体选择性 ,因其负载量大特别适用于对映体制备分离。本文对纤维素衍生物手性固定相的种类、影响手性选择性的因素以及手性识别的机理进行了较为全面的评述 ,并展望了研究前景     

A Comparative Analytical Study of Two New Liquid Crystals Used as Stationary Phases in GC

The investigation of the analytical properties of two new nematic sulphur-containing liquid crystals 5-(4-methoxyphenyl)-azophenyl)-2-butylthio-1,3,4-oxadiazole (Phase I) and 5-(4-(propoxyphenyl)-azophenyl)-2-butyl thio-1,3,4-oxadiazole (Phase II) and which comprise units of 1,3,4-oxadiazole instead of the aromatic cycles, was carried out by gas chromatography using glass capillary columns. For this purpose, many solutes belonging to various families and having different polarities and volatilities were injected. Comparison of the retention data of the studied components has shown that Phase II allowed a better separation than the other phase. The two liquid crystalline materials show a good separation of the studied isomers except for xylene.     

Separation Characteristics of Ionic Liquids Grafted Polymethylsiloxanes Stationary Phases for Capillary GC

Ionic liquids (ILs) grafted polymethylsiloxane (PMS) stationary phases (IL-PMS) for capillary gas chromatography (CGC) are described. The stationary phases were synthesized by grafting 1-vinyl-3-hexylimidazolium (VHIm) with either NTf ₂ ^? or PF₆ ^? anion to poly(methylhydrosiloxane) (PMS-VHIm-NTf₂, PMS-VHIm-PF₆) and coated statically onto fused-silica capillary columns. Separation characteristics of the stationary phases involving Abraham solvation parameters, separation ability and thermal stability were investigated. The obtained solvation parameters reveal that both IL-PMS stationary phases exhibited unique intermolecular interactions compared with either ILs or PMS due to the synergistic effect of ILs and PMS chemically combining together. The separation performance of the IL-PMS stationary phases was investigated by a Grob mixture and a complex mixture of 26 compounds of different types. The results show that the present stationary phases exhibit excellent resolution and selectivity for the analytes of interest with narrow and symmetric peak shapes. Thermal stability was also investigated by column bleed profiles with satisfactory results. The satisfactory chromatographic performance and thermal stability of the IL-PMS stationary phases suggest their great potential as a new type of CGC stationary phases.     

H PLC聚合物手性固定相

对近年来文献报道的高效液相色谱聚合物手性固定相及其在手性拆分中的应用予以综述 ,并阐述了聚合物手性固定相拆分机理的研究进展。     

联萘衍生物作为手性固定相在高效液相色谱中的应用

光学活性的联萘衍生物以其独特的立体化学性质作为优异的C2轴手性诱导源,已被广泛地应用到不对称催化反应和手性识别中。综述了联萘衍生物作为手性固定相在高效液相色谱中的应用。引用文献54篇。     

Liquid Crystals as Stationary Phases for High Performance Liquid Chromatography

Abstract

Liquid crystals have not yet been used as stationary phases in High Performance Liquid Chromatography. This is surprising since Gas Chromatography has demonstrated some remarkable separations, many of which are not possible with normal stationary phases, that have been achieved where liquid crystals have been employed as the stationary phase. The objective of the work reported here was to evaluate the chromatographic properties of several cholesteric liquid crystals as stationary phases in HPLC. Included in this study was an investigation of the feasibility of bonding a cholesteric moiety to a solid support for use in HPLC. The columns showed a dramatic increase in capacity factor for steroid molecules as the temperature of the column was increased.     

Liquid Crystals as Stationary Phases in Chromatography

The most correct analysis of the compositions of diverse analytes mixtures is significant for analytical studies in different fields; however, many prevalent analytes cannot be identified employing traditional partition gas chromatographic methods. Thus, the increasing requirements on analytes of isomeric compounds and the problems encountered in their separation demand a study of more diverse analytical systems which are characterised by higher selectivity. Therefore, the selectivity and polarities of various liquid crystals (rod-like, banana-shape, biforked, oxygen, sulphur, nitrogen, and metal containing molecules, Schiff-base, and polymeric dendrimers) employed as liquid crystalline stationary phases (LCSPs) have been discussed from both points of views, namely, their analytical applications and thermodynamic characteristics of infinitely diluted probes with different acceptor–donor properties. Extreme particular effort has been paid to the different interdependencies between the bound up chemical structures of liquid crystal molecules with their different acceptor–donor properties and the connected resolution capabilities in the interpretation of the probe—LCSP systems, on the basis of the \( { \ln }V_{g\left( T \right)} = f\left( {\frac{1}{T}} \right) \) and \( { \ln }\left( {\frac{{a_{1} }}{{w_{1} }}} \right)^{\infty } = f\left( {\frac{1}{T}} \right) \) dependencies, with regard to the LCSP compositions, which have been controlled by the counterbalancing of the enthalpy and entropy factors. The properties of binary systems composed of liquid crystalline poly(propyleneimine) dendrimers—rod-like molecules of liquid crystals and effects of the dendrimer structure, the chemical nature, and molecular size of the non-mesogens on the ability to dissolve in the liquid crystalline phases, have been interpreted. Practical applications of metallomesogenes and chiral stationary phases for analytical separation of different organic substances have also been taken into consideration.

     

Characterizations for Vinylimidazolium Based Ionic Liquid Polymer Stationary Phases for Capillary Gas Chromatography

Six polyvinylimidazolium based ionic liquids were prepared for use as stationary phases for gas chromatography. The influences of the attached side-chains (hexyl-, octyl- and phenylpropyl-) on the vinylimidazolium cations and of different counter ions (bromide, hexafluorophosphate, bis-trifluoromethanesulfonlyimide, and bis-trifluoroethanesulfonylimide) were studied. Linear solubility parameter experiments were conducted to characterize the specific interactions of these stationary phases. Some of the polymerized ionic liquid stationary phases exhibited unique structural selectivity. m-, and p-xylenes could be distinguished. The preparation of the polymerized ionic liquid column is simple and reliable. This work provides detailed information for designing polymerized ionic liquids, and shows that these materials have great potential extending the range of options for stationary phases in gas chromatography.     

离子液体在气相色谱固定相中的应用

本文综述了离子液体在气相色谱固定相中的发展过程。为提高固定相的使用温度、选择性和色谱柱效,离子液体先后经历多次制备方法的改善,本文主要介绍了小分子离子液体、大体积离子液体、柱内烯基咪唑聚合离子液体、物理混配离子液体和化学键合离子液体等非手性离子液体的合成进展;同时综述了由手性氨基酸、手性胺和键合环糊精合成的手性离子液体的研究进展;并比较各种离子液体用作色谱固定相时的稳定性及选择性差异。另外,对离子液体在二维气相色谱和快速气相色谱中的应用扩展作了总结,并展望离子液体作为新型分离材料在气相色谱固定相中的研究和应用前景。     

L-AlaC4NTf2手性离子液体作为新型气相色谱固定相的性能研究

合成了一种手性离子液体L-丙氨酸叔丁酯双三氟甲烷磺酰亚胺(L-AlaC4NTf2), 将其作为新型气相色谱固定相, 并与OV-1701按不同比例混合, 考察了它们的色谱性能. 研究结果表明, 该离子液体作为手性固定相的热稳定性高于175 ℃; 平均McReynolds常数为665; 在容量因子为1.02时, 理论塔板数可达每米1095块; 其对烷烃、醇类、酮类、芳香族化合物、位置异构体以及一些手性化合物具有良好的分离效果.     

芳香取代基结构对螺旋聚乙炔高效液相色谱手性固定相手性识别性能的影响

设计合成了3种源于脯氨酸的手性乙炔基单体——(S)-2-乙炔基-N-芳香胺基甲酰基吡咯烷. 在氯化降冰片二烯铑二聚体{[Rh(nbd)Cl]₂}-三乙胺催化下, 3种单体被转化为相应的光学活性螺旋聚合物. 用高效液相色谱评估了3种聚合物作为手性固定相(CSPs)对9种底物的手性识别性能. 以正己烷/异丙醇(体积比9∶1)为流动相时, 3种聚合物对3对种氢键给体分子苯偶姻(α=1.35~1.44)、 三氟-1-(9-蒽基)乙醇(α=1.11~1.53)、 2,2′-二羟基-1,1′-联萘(α=1.09~1.11)及乙酰丙酮钴(α=1.84~2.38)表现出很好的手性识别能力; 当以正己烷为流动相时, 3种聚合物都能立体选择性地识别氢键给体分子2,2-二甲基-1-苯基-1-丙醇(α=1.12~1.22), 聚[(S)-2-乙炔基-N-(2′-萘基胺基甲酰基)吡咯烷]能识别氢键受体分子2-苯基环己酮(α=1.11). 结合核磁共振波谱、 拉曼光谱、 旋光测试、 紫外吸收光谱和圆二色光谱及液相色谱等方法, 系统研究了芳香侧基结构与连接位置对聚合物螺旋构象和对映体选择性拆分能力的影响. 分子对接模拟结果表明, 1-萘基的空间位阻大于2-萘基且可促进形成更强的分子内氢键, 不利于大尺寸底物(如联萘酚)的手性拆分. 与苯基相比, 引入萘基有利于增强聚合物与底物间的π-π相互作用, 提高聚合物的立体选择性和手性识别能力.     

新型季磷离子液体气相色谱柱的制备及应用

选择季磷型离子液体为气相色谱固定相,采用静态法将其涂渍于纳米级SiO2预处理的毛细管内壁上制备成毛细管气相色谱柱.考察了此固定相的基本色谱性能和极性,并详细研究了其对多种化合物的分离性能和保留特点.研究表明,此该离子液体色谱柱的柱效为1381 plates/m,极性为559.6,与商品化的聚乙二醇(PEG20M)和硝基对苯二甲酸改性的聚乙二醇(FFAP)柱的极性相近.此固定相对给质子体化合物的保留作用明显强于PEG20M,并且其对芳香化合物的间位和对位异构体的分离选择性明显优于自制的PEG20M.此固定相对芳香位置异构体、烷烃、多环芳烃、氯苯、醇类等均具有较好的分离效果.     

Expanding the Applications of the Ionic Liquids as GC Stationary Phases: Plasticizers and Synthetic Musks Fragrances

The exceptional properties of the ILs make them ideal for gas chromatography stationary phases. New stationary phases exhibiting good separation selectivity, high efficiency, and high thermal stability are in high demand. Recently, several gas chromatographic capillary columns containing IL stationary phases of various polarities have been introduced on the market. The aim of this work is to extend the applications of the ILs as GC column coatings. The effectiveness of five different commercial IL columns (SLB™-IL59, SLB™-IL76, SLB™-IL82, SLB™-IL100 and SLB™-IL111) for the analysis of two different families of emerging contaminants of environmental concern (plasticizers and synthetic musk fragrances) has been explored. The results obtained for these two families of compounds are compared with the ones obtained when using a (5 %-phenyl)-methylpolysiloxane column. For three of these IL columns, applications have not yet been described. Good resolution for the most of the studied emerging pollutants belonging to five different analytical groups (adipates, phthalates, macrocyclic musks, nitromusks and polycyclic musks) was achieved in all the IL columns.

     

用液体有机硝酸盐作气相色谱固定相

选用二乙胺、三乙胺、正丙胺、异丙胺、正丁胺和异丁胺的硝酸盐作为气相色谱固定相,测得它们的使用温度范围均超过１００℃。上述液体有机盐对具有大偶极矩分子化合物或具有氢键成键能力的化合物（如醇类）有良好的选择性,特别对醇类异构体的分离效果更佳;对酮类及单官能团取代苯的分离效果更令人满意,但对烃类不适用。     

16种手性化合物在不同自制手性固定相上的拆分比较

采用高效液相色谱法,在自制的纤维素-三(3,5-二甲基苯基氨基甲酸酯)(ATEO-OD)、纤维素-三(4-甲基苯基氨基甲酸酯)(ATEO-OG)和纤维素-三(4-甲基苯基甲酸酯)(ATEO-OJ)3种手性柱上对16种不同结构的手性化合物进行了拆分和比较.试验结果表明:16个手性样品在这3种手性固定相上分别获得了不同程度的拆分,A TEO-OD对所分析样品具有更好的手性识别能力,ATEO-OG和ATEO-OJ的手性识别能力相当.