Enantiomer separation by CEC——Enantiomer separation by packed-capillary electrochromatography

Three chiral compounds were successfully separated in a short time with two enantiomer separation models on packed-capillary electrochromatography (CEC). (i) 75 μm I.D. capillaries were packed with 5 μm β-cyclodextrin (β-CD) chiral stationary phase (CSP). Effects of voltage, pH and concentration of organic modifier on electroosmotic flow (EOF) and chiral separations were investigated systematically. Enantiomers of a neutral compound (benzoin) and a neutral drug (mephenytoin) were separated within a short time with high efficiency. Efficiency of 32 000 theoretical plates per meter and resolution (R_s) of 1.42 were achieved for enantiomers of benzoin using a βCD packed column with 6.2 cm packed length. Efficiency of 45 000 theoretical plates per meter and R_s of 3.40 were obtained for enantiomers of mephenytoin. Especially, the enantiomer separation of mephenytion was performed in just 3.4 min with R_s of 2.60. (ⅱ) 75 μm I.D. capillary was packed with octadecylsilica particles (ODS). Chiral separat     

毛细管电色谱手性分离进展

 :比较全面地评述了毛细管电色谱(CEC)在手性拆分领域中的应用和发展,包括CEC的不同操作模式、手性试剂和手性固定相。92篇。     

胶束电动毛细管色谱法拆分肾上腺素对映体

胶束电动毛细管色谱法拆分肾上腺素对映体;电化学检测;对映体拆分     

氰醇类化合物对映体的气相色谱分离

对ＣＹＤＥＸ－β全甲基化β－环糊精毛细管柱上，对１４种手性氰醇对映体的乙酰化和三氟乙酰化衍生物，进行了气相色谱分离研究，比较了两种衍生方法的拆分效果，测定了实际合成样品的ｅ．ｅ．值，并对对映体拆分机理进行了一些探讨。     

Polysaccharide- and β-Cyclodextrin-Based Chiral Selectors for Enantiomer Resolution: Recent Developments and Applications

Polysaccharides, oligosaccharides, and their derivatives, particularly of amylose, cellulose, chitosan, and β-cyclodextrin, are well-known chiral selectors (CSs) of chiral stationary phases (CSPs) in chromatography, because they can separate a wide range of enantiomers. Typically, such CSPs are prepared by physically coating, or chemically immobilizing the polysaccharide and β-cyclodextrin derivatives onto inert silica gel carriers as chromatographic support. Over the past few years, new chiral selectors have been introduced, and progressive methods to prepare CSPs have been exploited. Also, chiral recognition mechanisms, which play a crucial role in the investigation of chiral separations, have been better elucidated. Further insights into the broad functional performance of commercially available chiral column materials and/or the respective newly developed chiral phase materials on enantiomeric separation (ES) have been gained. This review summarizes the recent developments in CSs, CSP preparation, chiral recognition mechanisms, and enantiomeric separation methods, based on polysaccharides and β-cyclodextrins as CSs, with a focus on the years 2019–2020 of this rapidly developing field.     

加压毛细管电色谱法分离1-甲基-3-苯基丙胺对映体

运用毛细管电色谱(pCEC)模式,以羟丙基-β-环糊精(HP-β-CD)作为手性选择剂,对1-甲基-3-苯基丙胺对映体进行手性分离。1-甲基-3-苯基丙胺对映体在最佳的条件下如:手性选择剂浓度10g/L、流动相配比:V(乙腈)∶V(磷酸盐体系)=60∶40溶液(5mmol/L)、背景电解质pH=7.6、柱温16℃和分离电压10kV达到了基线分离,该方法重现性好、简便、快捷。     

手性配体高效液相色谱法拆分扁桃酸对映体的热力学性质

手性配体;扁桃酸;对映体拆分;热力学性质     

脲衍生物型手性固定相拆分噻利洛尔对映体

用脲衍生物型手性固定相直接拆分了药物对映体噻利洛尔。优化的正相色谱流动相的组成为正己烷／１,２－二氯乙烷／乙醇（７７∶２１∶２,Ｖ／Ｖ／Ｖ）。实验表明,流动相中乙醇含量的改变对分离度产生了较大的影响;不同极性调节剂的使用表现出了不同的拆分效果。最后讨论了异构体的出峰次序,认为异构体与固定相的手性中心之一的氢键作用力是造成异构体分离的主要因素。     

吸附固定相电色谱和动态改性电色谱的手性分离

对动态改性电色谱手性分离进行了研究。电色谱柱填充强阴离子交换固定相（SAX0,添加在流动相中的磺化β－环糊精（S－CD）动态地吸陵于SAX填料表面,形成一层准手性固定相。色氨酸、阿托品和异博定对映体在本体系获得了很好的分离,它们的分离分别为2．06,10．1和1．96,对映体峰的柱效价于85,000塔板数／米和412,000塔板数／米之间。连续运行17次,死时间和色氨酸对映体的电色谱保留因子的相对标准偏差分别为0．53％,0．62％和0．69％。此外,以吸附于SAX填料的牛血清白蛋白和S－CD为手性固定相进行了电色谱手性分离的研究。在这两种体系下分离色氨酸对映体的分离度分别为3．86和2．97。吸附S－CD柱电色谱和动态改性电谱的重现性进行子比较,发现动态改性电色谱有更好的重现性。     

Enantiomer separation by capillary electrophoresis using DEAE-dextran and aminoglycosidic antibiotics

Summary Diethylaminoethyl (DEAE) dextran hydrochloride and three kinds of aminoglycosidic antibiotics; fradiomycin sulfate, kanamycin sulfate and streptomycin sulfate, were employed as chiral selectors in capillary electrophoresis, enantiomer separation. These selectors are cationic or basic because of amino functionality and therefore used for enantiomer separation of acidic compounds. To avoid adsorption of the basic or cationic selectors on the capillary inner surface, a coated capillary was employed. Among those tested, enantiomers of binaphthyl compounds and synthetic intermediates of diltiazem analogues were separated. Methanol addition was effective for the improvement of peak shape and resolution.     

离子对色谱法分离苯丙氨酸对映体

以苯甲酰氯为衍生试剂，将苯丙氯酸衍生为酰胺对映体，用奎宁作为手性离子对试剂，应用离子对色谱法，在硅胶柱上，成功地分离了ＤＬ－β－苯丙氨酸对映体，同时利用色谱保留值规律和光谱特征吸收曲线综合进行了定性分析。考察了流动相组成对保留值和分离选择性的影响，实验结果表明，在０．１９～０．７３ｍｍｏｌ／Ｌ范围内，奎宁浓度对保留值和分离选择性影响不大；而流动相中戊醇浓度之较小增加即可导致保留值与分离选择性下降；     

Single-Layered Chiral Nanosheets with Dual Chiral Void Spaces for Highly Efficient Enantiomer Absorption

Although considerable effort in recent years has been devoted to the development of two-dimensional nanostructures, single-layered chiral sheet structures with a lateral assembly of discrete clusters remain elusive. Here, we report single-layered chiral 2D sheet structures with dual chiral void spaces in which discrete clusters of planar aromatic segments are arranged with in-plane AB order in aqueous methanol solution. The chirality of the sheet is induced by the slipped-cofacial stacks of rectangular plate-like aromatic segments in the discrete clusters which are arranged laterally with up and down packing, resulting in dual chiral void spaces. The chiral nanosheets function as superfast enantiomer separation nanomaterials, which rapidly absorb a single enantiomer from a racemic mixture with greater than 99 % ee.     

Theoretical study of the separation mechanism of ionizable compounds in capillary electrochromatography

The migration mechanism of ionizable compounds in capillary electrochromatography (CEC) is more complicated than in high perfomance liquid chromatography (HPLC) due to the involvement of electrophoresis and the second chemical equilibrium. The separation mcchanism of ionizable compounds in CEC has been studied theoretically. The electrochromatographic capacity factors of ions (k’) in CEC and in the pressurized CEC are derived by phenomenologicul approach. The influence of pH, voltage, pressure onk’ is discussed. In addition, thek’ of weak acid and weak base are derivcd base on acid-base equilibrium and the influence of pH onk’ is studied theoretically. Project suppoted by the Excellent Young Scientist Award from the National Natural Science Foundation of China and the Natural Science Foundation of Lioanning Province.     

非甾体抗炎药对映体在多糖衍生物手性固定相上的拆分

在共价键合多糖类衍生物的手性固定相(Chiralpak IA,Chiralpak IB,Chiralpak IC)和涂敷型多糖衍生物的手性固定相(Chiralpak AD,Chiralcel OD)上,对非甾体抗炎药物(non-steroidal anti-inflammatory drugs,NSAIDs)进行了对映体拆分.色谱条件:流动相为10%异丙醇/正己烷(V/V)含0.1%三氟乙酸(Chiralpak AD,2%异丙醇/正己烷(V/V)含0.1%三氟乙酸(Chiralpak OD),异丙醇(四氢呋喃、乙酸乙酯、二氯甲烷)/正己烷/0.1%三氟乙酸(Chiralpak IA,Chiralpak IB,Chiralpak IC);流速为1.0 mL/min;紫外检测波长为254 nm.比较了非甾体抗炎药在直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)衍生的手性固定相Chiralpak IA和 Chiralcel AD,纤维素-三(3,5-二甲基苯基氨基甲酸酯)衍生的手性固定相Chiralpak IB和Chiralcel OD上的对映体拆分.结果表明,非甾体抗炎药在Chiralpak IA和Chiralpak IB上的分离效果普遍低于Chiralpak AD和Chiralcel OD.     

Effect of ion adsorption on CEC separation of small molecules using hypercrosslinked porous polymer monolithic capillary columns

Both poly(styrene-co-vinylbenzyl chloride-co-divinylbenzene) and poly(4-methylstyrene-co-vinylbenzyl chloride-co-divinylbenzene) monolithic columns have been hypercrosslinked and for the first time used to achieve capillary electrochromatographic separations. Although these columns do not contain ionizable functionalities, electroosmotic flow was observed due to adsorption of ions from a buffer solution contained in the mobile phase on the surface of the hydrophobic polymer. An increase of more than one order of magnitude was observed with the use of both monolithic polymers. The hypercrosslinking reaction creates a large surface area thus enabling adsorption of a much larger number of ions. Alkylbenzenes were successfully separated using the hypercrosslinked monolithic columns.     

Analytical and semipreparative separation of the enantiomers of new acetylcholinesterase inhibitors by high-performance liquid chromatography

Summary The resolution of the enantiomers of new acetylcholinesterase inhibitors by high-performance liquid chromatography (HPLC) was investigated on stationary phases containing cellulose tris-(3,5 methylphenylcarbamide) (Chiralcel OD). The effects of the mobile phase on retention, enantioselectivity and resolution were also studied. Ethanol and isopropanol were tested as organic modifiers and the influence of diethylamine was investigated. The effect of temperature on chiral separations was also studieded.     

Theoretical study of the separation mechanism of ionizable compounds in capillary electrochromatography

The migration mechanism of ionizable compounds in capillary electrochromatography (CEC) is more complicated than in high performance liquid chromatography (HPLC) due to the involvement of electrophoresis and the second chemical equilibrium. The separation mechanism of ionizable compounds in CEC has been studied theoretically. The electrochromatographic capacity factors of ions (k~*) in CEC and in the pressurized CEC are derived by phenomenologicai approach. The influence of pH, voltage, pressure on k~* is discussed. In addition, the k~* of weak acid and weak base are derived based on acid-base equilibrium and the influence of pH on k~* is studied theoretically.     

Single‐Layered Chiral Nanosheets with Dual Chiral Void Spaces for Highly Efficient Enantiomer Absorption

Although considerable effort in recent years has been devoted to the development of two‐dimensional nanostructures, single‐layered chiral sheet structures with a lateral assembly of discrete clusters remain elusive. Here, we report single‐layered chiral 2D sheet structures with dual chiral void spaces in which discrete clusters of planar aromatic segments are arranged with in‐plane AB order in aqueous methanol solution. The chirality of the sheet is induced by the slipped‐cofacial stacks of rectangular plate‐like aromatic segments in the discrete clusters which are arranged laterally with up and down packing, resulting in dual chiral void spaces. The chiral nanosheets function as superfast enantiomer separation nanomaterials, which rapidly absorb a single enantiomer from a racemic mixture with greater than 99 % ee.     

麦草伏甲酯对对映体的高效液相色谱分离

手性分离;麦草伏甲酯对对映体的高效液相色谱分离     

Enantiomer separation of 2-halocarboxylic acid esters by chiral complexation gas chromatography

The enantiomer separation of 2-halocarboxylic acid esters on two chiral nickel(II) bis-((perfluoroacyl)terpeneketonates) by complexation gas chromatography is described. The quantitative entiomer separation of branched 2-halocarboxylic acid esters is achieved with nickel (II) bis (3-(heptafluorobutanoyl)(1R, 2S)-pinan-4-onate) 1 while unbranched 2-halocarboxylic acid esters are preferably separated on nickel(II) bis(3-(heptafluorobutanoyl)-(1S)-10-methylenecamphorate) 2. The metal chelates 1 and 2 are accessible in both enantiomeric forms allowing the determination of the enantiomeric excess (ee) effective and reliable.