Separation Properties of a New Polysiloxane-Anchored β-Cyclodextrin Derivative as Gas Chromatography Stationary Phase

A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.

Separation of Enantiomers of Clopidogrel on Chiral Stationary Phases by Packed Column Supercritical Fluid Chromatography

A packed column supercritical fluid chromatography (SFC) method for the separation of clopidogrel enantiomers on a chiral stationary phase and CO2 with modifier as mobile phase has been developed at an analytical scale. Among 11 different 2 stationary phases the Chiral cel OD-H column showed by far the best separation properties. The influence of different modifiers, injection solvents, temperature, and pressure, and density of the fluid, respectively, on the separation behaviour has been studied. It was found that the separation behaviour strongly depends on the type of modifier and the modifier content. Temperature and pressure are of less influence.

Recent applications and chiral separation development based on stationary phases in open tubular capillary electrochromatography(2019–2022)

Capillary electrochromatography(CEC)plays a significant role in chiral separation via the double separation principle,partition coefficient difference between the two phases,and electroosmotic flow-driven separation.Given the distinct properties of the inner wall stationary phase(SP),the separation ability of each SP differs from one another.Particularly,it provides large room for promising applications of open tubular capillary electrochromatography(OT-CEC).We divided the OT-CEC SPs developed over the past four years into six types:ionic liquids,nanoparticle materials,microporous materials,biomaterials,non-nanopolymers,and others,to mainly introduce their characteristics in chiral drug separation.There also added a few classic SPs that occurred within ten years as supplements to enrich the features of each SP.Additionally,we discuss their applications in metabolomics,food,cosmetics,environment,and biology as analytes in addition to chiral drugs.OT-CEC plays an increasingly significant role in chiral separation and may promote the development of capillary electrophoresis(CE)combined with other instruments in recent years,such as CE with mass spectrometry(CE/MS)and CE with ultraviolet light detector(CE/UV).

Two Side Chain β-CD Polysiloxanes Used as New Stationary Phase for Chiral Separation by HRGC

Two new stationary phases : (Ⅰ) [bikis(2,6-di-O-pentyl-3-O-hex-6O-pentyl-3-O-methyl)-β-CD-polysiloxane] and (Ⅱ) [heptkis(2,6-di-O-methyl-3-O-hex-6-enyl)-β-CD-polysiloxane] were synthesized and successfully used for GC separation of chiral isomers.The possess high column efficiency and exhibit fine chiral separation ability.

A Good GC Stationary Phase for Separation of Xylene Isomers

An excellent separation of xylene isomers is reported using 2, 6-O-di-pentyl-3-O-acetyl-beta-CD as capillary stationary phase. The optimum conditions for the separation are also discussed.

Comparative Optical Separation of Racemic Ibuprofen by Using Chiral Stationary Phase

Ibuprofen is widely used as a non-steroidal anti-inflammatory drug and produced as racemic mixture. Its pharmacological activity resides only in S-(+)-enantiomer, and R-()-enantiomer is not only inactive but also has many side effects. Thus it is necessary to separate R-enantiomer from racemic ibuprofen. We studied optical separation of racemic Ibuprofen with chiral high performance liquid chromatography (HPLC). Out of three different chiral stationary phases, which were selected on the basis of structure and availability, two were found to be ef-fective. There was optimum eluent composition for each stationary phase for good resolution in optical separation. Resolution decreased with increase of eluent flow rate, but effect of injection volume on resolution was insignificant at high eluent flow rate.

Comparison of the performance of chiral stationary phase for separation of fluoxetine enantiomers

Separation of fluoxetine enantiomers on five chiral stationary phases （chiralcel OD-H, chiralcel OJ-H, chiralpak AD-H, cyclobond 1 2000 DM and kromasil CHI-TBB） was investigated. The optimal mobile phase compositions of fluoxetine separation on each column were hexane/isopropanol/diethyl amine （98/2/0.2, v/v/v）, hexane/isopropanol/diethyl amine （99/1/0. l, v/v/v）, hexane/isopropanol/diethyl amine （98/2/0.2, v/v/v）, methanol/0.2% triethylamine acetic acid （TEAA） （25/75, v/v; pH 3.8） and hexane/isopropanol/diethyl amine （98/2/0.2, v/v/v）, respectively. Experimental results demonstrated that baseline separation （Rs〉1.5） of fluoxetine enantiomers was obtained on chiralcel OD-H, chiralpak AD-H, and cyclobond I 2000 DM while the best separation was obtained on the last one. The eluate orders of fluoxetine enantiomers on the columns were determined. The first eluate by chiralcel OJ-H and kromasil CHI-TBB is the S-enantiomer, while by chiralpak AD-H and cyclobond 12000 DM is the R-enantiomer.

单生过程separationcutoff的基于特征值的判别准则

对于时间逆具有随机单调性的以{0,1,…,mn}({mn}为关于n单调增的自然数列)为状态空间且从0出发的单生过程族,利用其负转移速率矩阵第一非零特征值的正性及最快强平稳时的任意阶矩,可以由转移速率矩阵的特征值表示这些性质,得到该族马氏过程separation cutoff存在的一个基于特征值的判别准则,验证了Peres的乘积条件对于此类单生过程成立.

Separation of atropisomers by chiral liquid chromatography and thermodynamic analysis of separation mechanism

In the pharmaceutical industry, the analysis of atropisomers is of considerable interest from both scientific and regulatory perspectives. The compound of interest contains two stereogenic axes due to the hindered rotation around the single bonds connecting the aryl groups, which results in four potential configurational isomers(atropisomers). The separation of the four atropisomers was achieved on a derivatized β-cyclodextrin bonded stationary phase. Further investigation showed that low temperature conditions, including sample preparation(-70 °C), sample storage(-70 °C), and chromatographic separation(6 °C), were critical to preventing interconversion. LC-UV-laser polarimetric analysis identified peaks 1 and 2 as a pair of enantiomers and peaks3 and 4 as another. Thermodynamic analysis of the retention data indicated that the separation of the pairs of enantiomers is primarily enthalpy controlled as indicated by the positive slope of the van't Huff plot. The difference in absolute Δ(Δ H), ranged from 2.20 k J/mol to 2.42 k J/mol.

Simultaneous Chiral Separation Using a Combinatorial Molecular Imprinting Phase

Molecular imprinting chiral stationary phase against Cbz-L-Serine (Cbz-L-Ser) and Cbz-L-Alaine (Cbz-L-Ala) were prepared utilizing acrylamide + 2-vinylpyridine as combined basic functional monomers. Cross-selectivity was used to obtain simultaneous chiral separations of Cbz-DL-Ser and Cbz-DL-Ala by connecting two columns packed with Cbz-L-Ser and Cbz-L-Ala imprinted chiral stationary phase, respectively.

Optical transfer function analysis of circular-pupil wavefront coding systems with separable phase masks

This paper proposes a simple method to achieve the optical transfer function of a circular pupil wavefront coding system with a separable phase mask in Cartesian coordinates. Based on the stationary phase method, the optical transfer function of the circular pupil system can be easily obtained from the optical transfer function of the rectangular pupil system by modifying the cut-off frequency and the on-axial modulation transfer function. Finally, a system with a cubic phase mask is used as an example to illustrate the way to achieve the optical transfer function of the circular pupil system from the rectangular pupil system.

采用非稳相偏振滤波的DAS-VSP数据P/S波分离方法及其应用

分布式光纤声学传感(DAS)因成本低、易布设以及高密度采样等优势正成为重要的地震观测技术,尤其是越来越多地与垂直地震剖面(VSP)结合,用于主动地震勘探或被动地震监测.DAS传感器通过感知弹性波场产生的轴向应变或应变速率来观测地震波场振动.然而,目前单分量DAS-VSP数据未完整地记录地下弹性波场的三维矢量振动信号,因此如何从中分离出P波或S波用于后续地震成像与参数反演是重要且很有挑战的课题.以弹性波传播理论为基础,本文根据P波和S波的频散关系估算接收点处各自的偏振方向,通过随频率和空间位置变化的偏振滤波实现DAS-VSP数据的P/S波分离.理论模型合成数据与东海实际DAS-VSP数据实验结果表明,该方法能有效地将P波和S波信号从单分量DAS-VSP数据中分离出来,可为后续纵横波速度反演、PP与PS波成像提供关键的数据预条件处理.

纳米晶纤维素组装的手性介孔材料及其对手性药物的分离

纤维素纳米晶体(CNC)是由硫酸催化的纤维素水解制备的,根据纤维素的来源和水解条件,纳米晶体的直径约为5~15 nm,长度约为100~300 nm。CNC在水中可以形成具有手性向列型结构的液晶相。当干燥成固体薄膜时,CNC保持螺旋手性向列顺序并组装成层状结构。在CNC自组装过程中,可以添加溶胶-凝胶前体,如Si(OMe)_(4)。随着溶剂的蒸发,这些前体会发生水解和缩合,从而形成手性向列相二氧化硅/CNC复合材料。复合材料在空气中煅烧破坏纤维素模板,留下高表面积手性向列结构的介孔二氧化硅膜。此外,有机二氧化硅或二氧化钛薄膜也采用类似的方法得到。这些薄膜可用作滤光片、反射器和薄膜。最重要的是,合成的手性介孔二氧化硅可用作手性色谱固定相材料分离手性药物。结果显示,手性分离的效果显著,为CNC开发手性新材料提供了新方法。

手性多孔有机笼用作气相色谱固定相分离手性和非手性化合物

多孔有机笼(POCs)是一种新型的多孔分子材料,具有明确的分子内腔结构、丰富的主客体识别能力和良好的溶解性,因而在分子识别、气体吸附、传感、催化、色谱分离等多个领域受到广泛关注。本文由四(4-醛基苯基)乙烯和(R,R)-1,2-环己二胺通过席夫碱缩合反应合成了一种手性多孔有机笼(CPOC),采用静态涂敷法将其涂敷于毛细管柱内表面制备了气相色谱柱,测试了该柱对有机混合物、异构体以及手性化合物的分离能力。结果显示,该柱可以实现4种有机混合物(正构烷烃、芳香烃、正构醇和Grob混合物)中所有组分的基线分离;同时有9种二取代苯位置异构体以及包括结构异构和顺反异构在内的16种有机异构体在该柱上也获得了较好的分离。更重要的是,该柱还具有优秀的手性拆分性能,有12种手性化合物在该柱上得到了拆分,其中5种手性化合物(3-羟基丁酸乙酯、缬氨酸衍生物、谷氨酸衍生物、1,2-丁二醇二乙酸酯和1,2-环氧丁烷)获得了基线分离。将该柱与商品β-DEX 120柱的拆分效果相比,该柱可以拆分β-DEX 120柱不能拆分的3-羟基丁酸乙酯、缬氨酸衍生物、谷氨酸衍生物、1,2-环氧丁烷、环氧氯丙烷和环氧溴丙烷等6种手性化合物,说明其与β-DEX 120柱具有手性拆分互补性。研究表明,CPOC制备的毛细管柱对手性和非手性化合物都具有良好的分离能力。

用于分离单糖与寡糖的亲水色谱材料制备及应用进展

糖类化合物在食品科学、医药科学、生命科学等领域中发挥至关重要的作用。糖类化合物可分为单糖、寡糖和多糖,其中单糖和寡糖大多是可溶性糖,不仅可以充当结构物质,还具有抗氧化、抗癌、抗菌、抗病毒等多种生物活性。亲水作用色谱弥补了反相液相色谱在糖类化合物分离方面的不足。本文重点介绍了2017—2022年报道的适合分离分析单糖和寡糖的氨基键合固定相、酰胺类键合固定相、糖类键合固定相、两性离子键合固定相等亲水色谱固定相,并概述了乙腈含量、缓冲盐浓度、流动相pH值和柱温等色谱分离条件对亲水分离效果的影响,以期为单糖及寡糖的分离分析提供一定的参考。

二维金属-有机框架纳米片用作高效液相色谱手性固定相研究

采用溶剂热法合成出一种二维金属-有机框架纳米片Co-NH_(2)-BDC,将(1S)-(+)-10-樟脑磺酰氯衍生到Co-NH_(2)-BDC上,制备了手性材料Co-NH_(2)-BDC-(1S)-(+)-10-樟脑磺酰氯,并对Co-NH_(2)-BDC和手性材料Co-NH_(2)-BDC-(1S)-(+)-10-樟脑磺酰氯进行了表征。通过“网包法”制备了手性固定相,用于高效液相色谱(HPLC)对其拆分能力进行考察。Co-NH_(2)-BDC-(1S)-(+)-10-樟脑磺酰氯色谱柱共拆分了26种外消旋体和5种苯系位置异构体,且大部分手性化合物的分离效果较好,达到基线分离。该色谱柱在不同进样量和柱温下具有良好的分离能力和较好的重复性,说明Co-NH_(2)-BDC-(1S)-(+)-10-樟脑磺酰氯所制备的HPLC手性固定相分离效果良好,具有较好的应用前景。

R-(3,3′-二溴-1,1′-二萘基)-20-冠-6用作高分辨气相色谱手性固定相的研究

以R-联萘酚作为原料,合成R-(3,3′-二溴-1,1′-二萘基)-20-冠-6,用核磁共振和热重分析对R-(3,3′-二溴-1,1′-二萘基)-20-冠-6进行表征。将其与聚硅氧烷OV-1701混合,静态法制备毛细管手性柱,采用扫描电子显微镜考察了固定相涂敷性能。选用一些外消旋体、正构烷烃混合物、正构醇混合物、芳香烃混合物、位置异构体作为测试物,考察该柱子的气相色谱分离性能。结果表明该手性分离柱对这些有机物具有好的分离能力。

Enantiomer Separation of α-Dimethyl Dicarboxylate Biphenyl and Related Biphenyl Compounds by Normal Phase HPLC on Polysaccharide Based Chiral Stationary Phases

Cellulose tris(4-methylphenylcarbamate), amylosetris(3,5-di-methylphenylcarbamate) and amylose tris (phenylcarbamate) were prepared by the methodreported by Okamoto and were coated onto an aminopropylated mesoporous spherical silica gel. Thesefinal products were used as chiral stationary phases of high performance liquid chromatography forthe eighteen structurally related biphenyl compounds. The resolution was made using normal-phasemethodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, 2-pro-panol or1-butanol). The effects of various aliphatic alcohols in the mobile phase were studied. Thestructural features of the solutes that influence then- k′ were discussed. A dominant effect oftrifluoroacetic acid on chiral separation of acidic solutes was noted.

Chiral metal-organic frameworks-based materials for chromatographic enantioseparation

The homochiral compounds play an important role in human health and pharmaceutical industry.Currently,the chromatographic enantioseparation has become one of the most effective and practical approach to obtain pure enantiomers.Herein,the exploration of advanced materials,using as chromatographic chiral stationary phases for racemic separation,has attracted great attention.Thanks to their high enantioselectivity and controllable synthesis,the emerging chiral metal-organic frameworks (CMOFs)have been widely studied as the stationary phase in chromatographic technology.In this review,we will summarize the principles of synthetic strategies and mechanism of chiral microenvironment.In particular,the recent progress and research hotspot of CMOFs regarding as the chiral stationary phases in gas chromatography (GC),high-performance liquid chromatography (HPLC),and capillary electrochromatography (CEC),are elucidated systematically according to the published work.Last but not the least,we also highlight the challenges and perspectives of rational design of CMOFs,as well as their corresponding racemic separation.We envision that the review will provide a further understanding of CMOFs and facilitate the development of chromatographic enantioselective applications.

Separation performance of graphene oxide as stationary phase for capillary gas chromatography

Graphene oxide（GO） has attracted extensive attention due to its unique properties and potential applications.Here,we report the investigation of GO nanosheets as a stationary phase for capillary gas chromatographic（GC） separations.The GO column,fabricated by a new one-step coating approach,showed average McReynolds constants of 308,suggesting the medium polar nature of the GC stationary phase.The GO stationary phase achieves good separation for analytes of different types with good peak shapes,especially for H-bonding analytes,such as alcohols and amines.The different retention behaviors of GO stationary phase from the conventional stationary phase may originate from its multiple interactions with analytes,involving H-bonding,dipole-dipole,π-π stacking and dispersive interactions.Moreover,GO column showed good separation reproducibility with relative standard deviation（RSD%） less than 0.24%（n = 5） on retention times of analytes.