氨基酸衍生物对映体的高效液相色谱手性分离

通过在流动相中使用酸性添加剂,在由(S)-N-(2-萘基)丙氨酸衍生而成的手性固定相上直接分离氨基酸的3,5-二硝基苯甲酰衍生物,获得非常理想的分离效果。并在此工作的基础上对手性识别机理进行了初步探讨。另外,通过在不同构型的手性固定相上分离相同的溶质,证明在结构相同、构型相反的手性固定相上,对映体的出峰顺序是相反的。     

利用酰胺型手性固定相正相拆分β-受体阻滞剂对映体

利用酰胺型手性固定相正相直接拆分了β－受体阻滞剂阿替洛尔,讨论了三元流动相中１,２－二氯乙烷和甲醇含量的改变以及不同极性调节剂的使用对分离的影响。优化的流动相组成为Ｖ（正己烷）∶Ｖ（１,２－二氯乙烷）∶Ｖ（甲醇）＝６８∶２６∶６,并在探讨分离机理的同时比较了阿替洛尔、噻利洛尔和普萘洛尔３种β－受体阻滞剂在酰胺型手性固定相上拆分的结果     

扁桃酸及其类似物在全甲基环糊精固定相上的手性拆分

在全甲基β－环糊精（ＰＭＢＣＤ）和全甲基γ－环糊精（ＰＭＧＣＤ）手性固定相上,考察了扁桃酸酯、α－甲氧基扁桃酸酯、２－羟基－３－苯基丙酸酯和２－羟基－４－苯基丁酸乙酯的气相色谱手性分离行为。结果表明,所有研究的羟基羟基羧酸酯均可以在ＰＭＣＤ手性固定相上得到很好的手性分离,而ＰＭＧＣＤ对所研究的对映体没有任何手性拆分能力。结合和学参数,探讨了手性诉分机理。     

一种手性中间体在键合型和涂覆型纤维素手性固定相上的拆分

制备了涂覆型和键合型纤维素-(3, 5-二甲基苯基氨基甲酸酯)固定相, 分别在制备的纤维素手性固定相上成功地拆分了一种手性中间体, 通过考察流动相中的改性剂(醇、四氢呋喃、三氯甲烷)对手性拆分的影响, 优化了手性中间体在两种手性固定相上的色谱分离条件, 并比较了手性中间体在涂覆和键合型纤维素手性固定相上的拆分. 结果表明, 涂覆型和键合型手性固定相对这种手性中间体均有较好的拆分效果, 在150 mm的色谱柱上, 这两种手性固定相对这种手性中间体的拆分能力相差不大, 但键合型固定相上可选择的流动相范围更广.     

脲衍生物型手性固定相分离α－氨基酸对映体的研究

 利用脲衍生物型手性色谱柱，作正相和反相液相色谱拆分Ｎ－３，５－二硝基苯甲酰化氨基酸丁酯衍生物。结果表明，正相色谱的手性分离效果比反相色谱要好得多，并且手性洗脱顺序完全相反。认为在固定相上对拆分起主要作用的可能是（Ｒ）－１－（α－萘基）乙胺部分的手性碳原子，而另外一个手性碳原子在拆分过程中起辅助作用。流动相在拆分过程中起着很重要的作用。     

衍生化环糊精键合固定相色谱保留和手性识别机理的研究（I）

合成了苯基氨基甲酸酯衍生化β－环糊精键合固定相,１４个α－氨基膦酸酯类化合物首次在该固定相和商品化的（Ｓ）－（＋）－萘乙基氨基甲酸酯衍生化β－环糊精固定相上进行液相色谱手性分拆。通过定量结构－对映异构体保留关系对比研究了两种不同的环糊精类固定相上可能的色谱保留和手性识别机理。     

脲衍生物型手性固定相分离α－氨基酸对映体的研究

利用脲衍生物型手性色谱柱，作正相和反相液相色谱拆分Ｎ－３，５－二硝基苯甲酰化氨基酸丁酯衍生物。结果表明，正相色谱的手性分离效果比反相色谱要好得多，并且手性洗脱顺序完全相反。认为在固定相上对拆分起主要作用的可能是（Ｒ）－１－（α－萘基）乙胺部分的手性碳原子，而另外一个手性碳原子在拆分过程中起辅助作用。流动相在拆分过程中起着很重要的作用。     

3种芳氧苯氧丙酸类除草剂在CDMPC与万古霉素手性固定相上的对映体分离

在纤维素三（3,5-二甲基苯基氨基甲酸酯）（CDMPC）手性柱上成功分离了3种高效芳氧苯氧丙酸类除草剂——稳杀得、千金和禾草灵。正相系统下,分别考察了流动相醇类添加剂的种类、浓度以及溶质结构对手性分离的影响,3种溶质中千金的保留最强而禾草灵的分离效果最好。并在万古霉素手性固定相上对3种芳氧苯氧丙酸类除草剂进行了手性拆分。在正相流动相中,它们在万古霉素手性固定相上的手性分离效果明显不如在CDMPC上的好。探讨了2种手性固定相对3种溶质的手性识别机理。     

大环抗生素手性固定相拆分盐酸马布特罗对映体

基于三种大环抗生素类手性固定相Chirobiotic V,T和R,利用高效液相色谱法对盐酸马布特罗对映体进行了拆分;考察了洗脱模式、流动相组成、柱温等因素对分离的影响,对分离结果进行了比较,对分离机制进行了探讨.结果表明,盐酸马布特罗对映体在Chirobiotic R手性固定相上不能实现分离,在Chirobiotic V和T手性固定相上均可实现较好的基线分离.最佳色谱条件为:新极性有机相模式,流动相甲醇-冰醋酸-三乙胺(100∶0.01∶0.01,V/V/V),流速1.0mL/min,柱温20℃;相应的分离度分别可达3.08和3.73.与此同时,盐酸马布特罗对映体与大环抗生素类固定相之间的离子相互作用是实现对映体分离的最主要分离机制.     

大环抗生素手性固定相拆分克伦普罗对映体及分离机制研究

应用三种大环抗生素类手性固定相Chirobiotic V、Chirobiotic T和Chirobiotic R,采用高效液相色谱法对盐酸克伦普罗对映体进行了拆分研究。实验考察了洗脱模式、流动相组成、柱温等因素对分离的影响,对分离结果进行了比较,并对其分离机制进行了探讨。结果表明,盐酸克伦普罗对映体在Chirobiotic R手性固定相上不能实现分离,在Chirobiotic V和Chirobiotic T手性固定相上,最佳色谱条件为:新极性有机相模式,流动相为甲醇-乙酸-三乙胺(100∶0.01∶0.01,V/V/V),流速:1.0mL/min,柱温:20℃,分离度可分别达到2.00和2.13。实验证明,盐酸克伦普罗对映体与大环抗生素类固定相之间的离子相互作用是实现对映体分离的最主要分离机制。     

Synthesis of novel chiral imidazolium stationary phases and their enantioseparation evaluation by high-performance liquid chromatography

Two novel chiral stationary phases (CSPs) were prepared by bonding chiral imidazoliums on the surface of silica gel. The chiral imidazoles were derivatized from chiral amines, 1-phenylethylamine and 1-(1-naphthyl)ethylamine. The obtained CSPs were characterized by Fourier Transform Infrared (FT-IR) spectroscopy and elemental analysis (EA), demonstrating the bonding densities of CSP 1 and CSP 2 were 0.43 mmol g⁻¹ and 0.40 mmol g⁻¹, respectively. These two CSPs could be used to availably separate 8 pharmaceuticals, 7 mandelic acid/its derivatives, 2 1-phenylethylamine derivatives, 1 1,1′-bi-2-naphthol, and 1 camphorsulfonic acid in high-performance liquid chromatography (HPLC). It is found that CSP 1 could effectively enantioseparate most chiral analytes, especially the acidic components, while CSP 2 could enantiorecognize all chiral analytes, although a number of components did not achieve baseline separation. Additionally, the effects of mobile phase composition, mobile phase pH and salt content, chiral selector structures, and analyte structures on the enantiorecognitions of the two CSPs were investigated. It is found that high acetonitrile content in mobile phases was conducive to enantiorecognition. Mobile phase pH and salt content could alter the retention behaviors of different enantiomers of the same chiral compound, resulting in better enantioresolution. Moreover, both chiral selector structures and substituted groups of analytes played a significant role in the separation of chiral solutes.     

Comparative Enantioseparation of Seven Amino Alcohols on Teicoplanin‐Based Chiral Stationary Phases

Abstract

The macrocyclic antibiotics represent a relatively new class of chiral selectors in separation science and teicoplanin‐based chiral stationary phases (CSP) have been used successfully in a number of applications in high‐performance liquid chromatography. In the present studies, we self‐prepared two bonded CSPs–teicoplanin (TE) and teicoplanin phenyl isocyanate (TE‐Phe). Seven amino alcohols, propranolol, bisoprolol fumarate, atenolol, salbutamol, isoproterenol, metoprolol, and labetalol were enantioseparated on both self‐made CSPs using methanol as mobile phase and acetic acid (HOAc) and triethylamine (TEA) as mobile phase additives. On both CSPs, the different enantioseparation behavior of analytes with different structure was compared. The influence of the concentration of mobile phase additives (HOAc and TEA) on the enantioseparation was investigated. In all conditions, the retention factors (k′) of seven analytes on TE‐Phe CSP were larger than that on TE CSP. However, the separation factors (α) and resolutions (Rs) on TE‐Phe CSP were smaller than that on TE CSP. The results indicated that the derivatized TE‐Phe CSP is not efficient as original teicoplanin CSP. Our observations also suggested that, for teicoplanin‐based CSPs, π‐π interactions and dipole‐dipole between solutes and CSPs mainly contribute to the retention of solutes on CSPs while hydrogen bonding and steric interactions play important roles in the chiral recognition for teicoplanin‐based CSPs.     

Doubly tethered tertiary amide linked and ionically bonded diproline chiral stationary phases

Oligoproline chiral stationary phase (CSP) is a new class peptide chiral stationary phase. Many proline chiral stationary phases with different proline chain lengths and linkers have been prepared and evaluated. However, the doubly tethered and ionic type linkers have not been adequately investigated. In this study, covalently and ionically bonded chiral stationary phases with doubly tethered linker were prepared and characterized. The new covalently bonded doubly tethered diproline CSP was applied successfully to resolve various enantiomers of acidic, basic, and neutral compounds with phenyl, naphthyl, anthryl, or similarly sized groups. The enantiorecognition performances of singly and doubly tethered diproline CSPs were comparable. Variation of the type and content of organic modifiers in hexane or heptane mobile phase showed that the branch alcohols such as 2‐propanol and 2‐butanol, 1,2‐dichloroethane, methyl tert‐butyl ether, and ethyl acetate in the mobile phase enhanced chiral separation. End‐capping on doubly tethered diproline CSP did not always improve the separation factor and resolution. Due to the rigid structure of the double tether, the enantioseparation ability of ionically bonded diproline CSP was well expressed to some analytes.     

联苯类对映体在直链淀粉类手性固定相上的高效液相色谱法直接拆分

 涂敷直链淀粉 三 (3,5 二甲基苯基氨基甲酸酯 )于自制的球形氨丙基硅胶上 ,制备了手性固定相。用该固定相直接拆分了一系列外消旋联苯类保肝药物 ,考察了一系列伯醇 (乙醇、正丙醇、正丁醇 )和异丙醇等流动相改性剂对保留和立体选择性的影响 ,讨论了固定相对样品的作用机理。     

Separation of racemic 2,4-dinitrophenyl amino acids on carboxymethyl-β-cyclodextrin coated zirconia in RPLC

We report preparation and use of carboxymethyl-β-cyclodextrin-coated zirconia as a chiral stationary phase (CSP) for separation of enantiomers of 2,4-dinitrophenyl (DNP) amino acids in reversed-phase high performance liquid chromatography. The CSP showed good enantioselectivity for some of the amino acids studied. Effects of pH and amount of methanol in mobile phases on retention and enantioselectivity for the analytes were examined.     

Chromatographic evaluation and comparison of three beta-cyclodextrin-based stationary phases by capillary liquid chromatography and pressure-assisted capillary electrochromatography

Enantiomer separations were performed on three beta-cyclodextrin-based chiral stationary phases (CSP) containing the pernaphthylcarbamoylated beta-cyclodextrin (CSP 1), peracetylated beta-cyclodextrin (CSP 2) and permethylated beta-cyclodextrin (CSP 3) as chiral selectors by capillary liquid chromatography and pressure-assisted capillary electrochromatography in this study. Triethylammonium acetate/MeOH or phosphate buffer/MeOH was used as the mobile phase. The experimental factors affecting chiral separations have been examined for each CSP, including pH of the buffers, methanol content and applied voltage. Under optimal separation conditions, a number of racemic compounds were resolved into their enantiomers on three cyclodextrin-based CSP. A comparative study on the performance of three CSP revealed the presence of carbonyl functional groups as well as aromatic rings in the cyclodextrin derivatives, enhanced the interaction between the analytes and CSP, and thus improved enantioselectivity of the CSP.     

Effect of analyte lipophilicity on the resolution of α‐ and β‐amino acids on liquid chromatographic ligand exchange chiral stationary phases

Separation of the two enantiomers of racemic α‐ and β‐amino acids on two ligand exchange chiral stationary phases (CSPs) prepared previously by covalently bonding sodium N‐((S)‐1‐hydroxymethy‐3‐methylbutyl)‐N‐undecylaminoacetate or sodium N‐((R)‐2‐hydroxy‐1‐phenylethyl)‐N‐undecylaminoacetate on silica gel was studied with variation of the organic modifier (methanol) concentration in the aqueous mobile phase. In particular, the variation of retention factors with changing organic modifier concentration in the aqueous mobile phase was found to be strongly dependent on both the analyte lipophilicity and the stationary phase lipophilicity. In general, the retention factors of relatively lipophilic analytes on relatively lipophilic CSPs tend to increase with increasing organic modifier concentration in the aqueous mobile phases while those of less lipophilic or hydrophilic analytes tend to increase. However, only highly lipophilic analytes show decreasing retention factors with increasing organic modifier concentration in the aqueous mobile phase on less lipophilic CSPs. The contrasting retention behaviors on the two CSPs were rationalized by the balance of the two competing interactions, viz. hydrophilic interaction of analytes with polar aqueous mobile phase and the lipophilic interaction of analytes with the stationary phase.     

奎宁-冠醚组合型手性固定相直接拆分氨基酸的机理

合成了一种新型奎宁-冠醚组合型手性固定相(QN-CR CSP)并用于氨基酸手性对映体的直接拆分,该固定相对12种氨基酸对映体有良好的手性拆分能力。基于氨基酸手性识别中离子交换和络合的协同作用,建立了一种新型的等温吸附模型。通过迎头特殊点洗脱法(FACP)测定色氨酸(Trp)在不同金属离子添加剂条件下的等温吸附线,验证了模型的合理性。流动相中的Li⁺、Na⁺、K⁺等金属离子与氨基酸竞争固定相中的冠醚络合位点,随着金属离子与冠醚的络合作用力和络合吸附平衡常数增大,固定相对Trp的手性拆分能力下降。该模型的建立对理解氨基酸在此类固定相中的手性保留行为以及固定相结构的进一步优化具有重要意义。     

Liquid chromatographic separation of the enantiomers of beta-amino acids on a ligand exchange chiral stationary phase

A liquid chromatographic ligand exchange chiral stationary phase (CSP) derived from (S)-leucinol was applied in the separation of the enantiomers of 12 beta-amino acids. The resolution was quite successful especially for the enantiomers of beta-amino acids containing aromatic functional group in the side chain. The chromatographic resolution behaviors were dependent on the organic modifier and Cu(II) concentration in aqueous mobile phase and the column temperature.