基于巯基-烯点击化学法的β-环糊精固定相多模式色谱保留行为研究

基于巯基硅胶与单取代-6A-烯丙氨基-β-环糊精的巯基-烯点击化学反应,制备了β-环糊精(Click TE-CD)共价键合固定相。元素分析结果表明β-环糊精被成功键合到硅胶表面。以黄酮苷类化合物为模型,考察了Click TE-CD固定相在亲水、反相和超临界流体色谱等分离模式下的色谱保留行为。黄酮苷类化合物保留时间随流动相中乙腈含量的变化呈现典型的U型曲线,表明Click TE-CD固定相具有亲水/反相的双重保留特性。应用几何学方法测得Click TE-CD固定相在反相/亲水、亲水/超临界、反相/超临界混合模式下的正交性分别为69.8%、50.8%、50.8%。对比复杂中药样品降香提取物在反相、亲水、超临界等模式下的分离情况,结果表明Click TE-CD固定相在分离中药复杂样品方面具有极大潜力,可以在一根色谱柱上通过分离模式的改变,实现二维液相色谱的分离。Click TE-CD固定相不同分离模式的分离性能和较好的正交性表明该固定相具有在液相色谱方法发展和二维液相色谱分离方面应用的潜力。     

苯乙烯和马来酸酐包夹硅胶弱阳离子色谱柱的制备及其应用

用马来酸酐包夹硅基制备出一种新型弱阳离子色谱柱填料,它具有良好的色谱性能,可同时分离一价、二价金属阳离子。论述了固定相的制备条件。采用所制备的固定相对热电厂锅炉水样中的阳离子进行了测定。     

环糊精手性分离固定相在手性药物的液相色谱和毛细管柱电色谱分析中应用的研究进展

对环糊精手性分离固定相在手性药物的液相色谱和毛细管电色谱法分析中应用的近期研究进展(主要从2008年1月至2013年7月间)情况进行综述。内容主要涉及此类固定相的合成方法,选择性功能基团的固定以及新型环糊精手性分离固定相在液相色谱及毛细管电色谱等方面的应用情况,并对其发展前景作了简述(引用文献49篇)。     

手性固定相毛细管电色谱在手性药物分离中的应用研究进展

综述了多糖衍生物、蛋白质、大环类、Prikle型、配体交换和分子印迹聚合物为手性固定相在毛细管电色谱分离手性药物中的应用.分析了各类手性固定相的分离机理,引用文献62篇.     

多糖类手性固定相在色谱中的应用

手性色谱技术是最重要的手性分离方法之一,它不仅可以快速地分析对映体纯度,也可以用于大量制备光学异构体。设计和发展高效的固定相是手性色谱技术的核心。在诸多的手性固定相中,多糖类手性固定相因品种繁多、耐用而被广泛应用。本文综述了多糖类手性固定相在高效液相色谱、模拟移动床色谱、超临界流体色谱及膜分离中的应用。共引用文献52篇。     

多糖衍生物类固定相在高效液相色谱手性分离中的应用进展

评述了多糖衍生物手性固定相在高效液相色谱手性分离中的应用进展，介绍了多糖衍生物手性固定相的主要类型，阐述了手性拆分机理和影响手性拆分的因素，引用文献66篇。     

聚硅氧烷包夹聚合硅基高效液相色谱固定相的表征及其色谱性能

利用元素分析、红外光谱、扫描电镜及汞压吸附法对制备的聚硅氧烷包夹硅基反相高效液相色谱固定相进行了表征,给出了该固定相的结构信息及其与色谱性能的关系;用滴定法测定了该固定相表面硅羟基数目;考察了该固定相对碱性化合物的分离性能;由表征和色谱性能考察结果可知,该固定相表面的羟基基本被覆盖,因此,可在碱性流动相中长期使用。     

3,4-二(3-苯氧基-4-氟苯基)-2,5-二苯基苯基接枝聚硅氧烷气相色谱固定相的合成与表征（英文）

合成了一种耐高温的3,4-二(3-苯氧基-4-氟苯基)-2,5-二苯基苯基接枝聚硅氧烷(DPFP)固定相,使用静态涂渍法将其涂渍到毛细管柱内壁上,制成气相色谱柱。分离裂解乙烯的色谱图显示DPFP固定相在360℃时仍具有良好的分离能力。DPFP固定相的柱效为3 324块/米(保留因子(k)4.24,萘,0.25 mm i.d.)。麦克雷诺常数计算结果显示DPFP固定相属中等极性。溶剂化参数模型结果显示DPFP固定相与溶质之间的主要作用力为偶极-诱导偶极作用力、氢键碱性作用力。Grob试剂分离结果显示DPFP色谱柱具有良好的选择性与惰性。另外,芳香族同分异构体、苯取代物、多环芳烃、脂肪酸酯及脂肪醇都得到了良好的分离,表明DPFP固定相在应用方面有巨大的潜力。     

离子交换纤维为固定相的离子色谱研究

〕研究了离子交换纤维做固定相在离子色谱中的应用。结果表明,用VS-2型阴离子交换纤维和VS-型阳离子交换纤维分别填充分离柱和抑制柱,与树脂柱具有相同的效果,而纤维柱的阻力仅为树脂柱的十分之一左右。我们认为用离子交换纤维做固定相对离子色谱具有实际意义。     

基于共价－有机骨架固定相的色谱分离应用研究进展

共价－有机骨架材料（COFs）是一类由轻质元素通过共价键形成的多孔材料,具有比表面积大、稳定性好、孔径可调、功能多样、结构可修饰等特点,在分析化学领域如样品前处理和色谱分离等方面显示出了良好的应用前景。其中COFs作为新颖色谱固定相在高效液相色谱、气相色谱和毛细管电色谱分离应用研究也逐渐引起了人们的关注。色谱分离所用COFs均具有良好的化学稳定性,但比表面积、孔径和性质各异,适用于分离不同类型的目标物如有机小分子、同分异构体和手性化合物等。该文综述了近年来以COFs为固定相的色谱分离应用研究进展,包括基于COFs的色谱固定相/色谱柱的制备及其色谱分离应用,并对其进行了展望。     

Polymer encapsulated staionary phases: Advantages,properties and selectivities

Chromatographia - By copolymerization of vinyl modified silica with acrylic acid derivatives stationary phases with imporved stability and optimum performance for the separation of basic solutes,...     

Characterization of several stationary phases prepared by thermal immobilization of poly(methyltetradecylsiloxane) onto silica surfaces

Variations of a thermal immobilization procedure using poly(methyltetradecilsiloxane) and silica produced fourteen stationary phases with carbon contents of 4-18%. The stationary phases were chromatographically evaluated with the Engelhardt, SRM 870 and Tanaka tests. Classifications using USP and Euerby procedures indicate that the new immobilized phases are different from most commercial phases although there was some similarity with phases that have high ion-exchange interactions. The retention mechanism involved in the separation of basic solutes on several of the new stationary phases was studied by varying pH, type of Lewis base and the ionic strength of the eluent. The separations are strongly influenced by the chemistry of the accessible free silanols. The stationary phases present good selectivity at intermediate pH where the basic analytes were protonated, suggesting use of intermediate pH for these separations. Stability tests show that the stationary phases have poor stability at very high pH, even at 23°C, but good stability in acidic mobile phases, even at 75°C, as expected for an immobilized polymer stationary phase.     

Separation behavior of basic compounds on unbonded silicon oxynitride and silica high‐performance liquid chromatography stationary phases with reversed‐phase eluents

Unbonded silicon oxynitride and silica high‐performance liquid chromatography stationary phases have been evaluated and compared for the separation of basic compounds of differing molecular weight, pK_a, and log D using aqueous/organic mobile phases. The influences of percentage of organic modifier, buffer pH, and concentration in the mobile phase on base retention were investigated on unbonded silicon oxynitride and silica phases. The results confirmed that unbonded silicon oxynitride and silica phases demonstrated excellent separation performance for model basic compounds and both the unbonded phases examined possessed a hydrophobic/adsorption and ion‐exchange character. The silicon oxynitride stationary phase exhibited high hydrophilicity compared with silica with a reversed‐phase mobile phase. An ion‐exclusion‐type mechanism becomes predominant for the separation of three aimed bases on the silicon oxynitride column at pH 2.8. Different from silicon oxynitride stationary phase, no obvious change for the retention time of three model bases on silica stationary phase at pH 2.8 can be observed.     

Some new selective stationary phases for RP-HPLC

At the present time, more complex analyses of apolar compounds with similar chemical structures or of polar compounds, especially basic ones, having diverse properties require more selective stationary phases having better stabilities. This paper describes several new stationary phases with directed selectivities that were prepared by immobilizing two different phenyl group-containing siloxanes and a trifluoropropyl-containing siloxane onto chromatographic silica and, in the case of the fluorinated siloxane, onto zirconized silica, using thermal treatment or microware radiation. The chromatographic properties and stabilities of these new phases were determined and several applications were evaluated. The phenyl-containing phases showed excellent characteristics related to the separation of several different types of aromatic compounds while the fluorinated phases, which present a more polar character, revealed selectivity for the separation of positional isomers as well as for a mixture of basic pharmaceuticals. Stability tests indicate that immobilization of the polysiloxanes increases column lifetimes by making the stationary phases less susceptible to dissolution, while the phases immobilized with microwave radiation were somewhat more stable than those immobilized by thermal treatments.     

Effect of chromatographic conditions on the separation and system efficiency for HPLC of selected alkaloids on different stationary phases

Retention parameters of alkaloid standards were determined on different stationary phases, i.e., octadecyl silica, base-deactivated octadecyl silica, cyanopropyl silica, preconditioned cyanopropyl silica, and pentafluorophenyl, using different aqueous eluant systems: acetonitrile-water mixtures; buffered aqueous mobile phases at pH 3 or 7.8; and aqueous eluants containing ion-pairing reagents (octane-1-sulfonic acid sodium salt and pentane-1-sulfonic acid sodium salt) or silanol blockers (tetrabutyl ammonium chloride and diethylamine). Improved peak symmetry and separation selectivity for basic solutes was observed when basic buffer, ion-pairing reagents, and, especially, silanol blockers as mobile phase additives were applied. The best separation selectivity and most symmetric peaks for the investigated alkaloids were obtained in systems containing diethylamine in the mobile phase. The influence of acetonitrile concentration and kind and concentration of ion-pairing reagents or silanol blockers on retention, peak symmetry, and system efficiency was also examined. The most efficient and selective systems were used for separation of the investigated alkaloids and analysis of Fumaria officinalis and Glaucium flavum plant extracts.     

HPLC-separation of enantiomers using quinine,covalently bonded to silica as stationary phase

Summary Stationary phases for chiral separations have been synthesized by chemical modification of porous small particle silica using new procedures of fixation of the chiral moiety. So called pre-polymers of the methylpolysiloxane polysiloxane type are immobilized on silica surfaces by different procedures. These pre-polymers are substituted by chiral groups. Their synthesis is done externally i.e. not in-situ on the support surface. The immobilization on the silica surface is achieved by crosslinking and/or by chemical bonding. Anchor groups within the pre-polymer (e.g. SiH) as well as on the silica surface (SiOH) give rise to the chemical bonding therewith. Chiral phases with quinine as the chiral moiety were obtained which show high separation efficiency as well as chemical stability, in addition to the enantiomeric selectivity required for the separation of certain types of aliphatic and aromatic alcohols. Presented at the 16th International Symposium on Chromatography, Paris, September 1986     

Preparation and characterization of a new C18 urea phase based on titanized silica

A new stationary phase containing embedded urea groups (-NH-C(O)-NH-) was prepared by a procedure based on the synthesis of a trifunctional C18 urea-alkoxysilane, followed by modification of titanized silica and further endcapping to evaluate if the embedded group would minimize the higher retention and tailing for basic compounds seen with C18 titanized silica phases. Infrared, 13C and 29Si spectroscopies were employed to characterize the C18-urea titanized silica phase. Chromatographic evaluations used hydrophobic, polar and basic compounds to verify the effects of the polar urea groups embedded in the C18 urea phase. The chromatographic parameters, especially for the separation of basic compounds, compare favorably with those obtained on a C18 titanized silica stationary phase, prepared by silanization of titanized silica with octadecyltrimethoxysilane.     

Liquid crystalline polymers as stationary phases. IV. Chemical bonding and immobilization of the polymer on silica characterization by solid-state nuclear magnetic resonance spectroscopy

Chemical bonding reaction and immobilization through low energy radiation (heating) have been investigated to fix a side-chain liquid crystalline polymer (SC-LCP) on silica particles in order to use the resulting modified silica in normal-phase HPLC. Highly stable chromatographic stationary phases are observed under excellent polymer solvent flow conditions (THF) for both methods and better column efficiencies are also exhibited towards PAHs' separation compared to the classical coated stationary phase. The characterization of these new stationary phases and the rationale for improved column stability have been investigated by solid state 13C and 29Si CP/MAS NMR spectroscopy. It is clearly shown that the chemical bonding is achieved by the classical hydrosilylation reaction between PHMS chains and vinyl modified silica. The bonded polymer is likely a copolymer than a homopolymer. The immobilization of the SC-LCP by heating results in the breaking of Si-O-Si bonds of the polysiloxane chain after the attack of the silica surface silanols. Applications to fullerenes and carotenes separation of these bonded stationary phases are compared to the separation power of a classical monomeric C18 stationary phase in NP-HPLC as n-hexane-toluene or methyl-tertiobutyl ether-methanol mixtures.     

High-performance liquid chromatographic stationary phases based on poly(methyloctylsiloxane) immobilized on silica. III. Stability evaluations

Several reversed-phase materials for high-performance liquid chromatography were obtained by deposition of poly(methyloctylsiloxane) (PMOS) on HPLC silica particles, followed by immobilization using different procedures. Each phase had characteristic physicochemical and chromatographic properties. The present work evaluates the stability of these phases with both neutral and basic mobile phases. All of the stationary phases were quite stable to neutral mobile phase, with less stability at higher pH. However, one thermally immobilized phase presented high stability even at an elevated temperature with a pH 10.0 mobile phase.     

Development of acid stable, hyper-crosslinked, silica-based reversed-phase liquid chromatography supports for the separation of organic bases

A new generation of extremely acid stable "hyper-crosslinked" (HC) phases have been developed with good plate counts for basic drug separations. In our previous work, we successfully developed an approach for synthesizing HC stationary phases on silica substrates using aluminum trichloride catalyzed Friedel-Crafts (F-C) chemistry to improve the stability of silica-based RPLC stationary phases at low pH. However, the performance of basic analytes on these HC phases under acidic conditions was unusually poor compared to that of conventional silica-based C18 phases. The effects of the specific F-C catalysts used and the specific silica substrate on the chromatographic properties of HC phases have been studied. Modified synthetic strategies that give both good observed plate counts for basic analytes under acidic conditions and very good low pH stability without compromising other chromatographic properties of the hyper-crosslinked phases have been developed. Replacement of aluminum trichloride with tin tetrachloride as the catalyst for the F-C chemistry and use of a very high purity silica result in significantly improved plate counts for basic analytes. In formic acid buffered mobile phases, which are highly compatible with electrospray ionization LC-MS, basic analytes showed much better performance on the tin tetrachloride catalyzed HC phases than on any conventional commercial phase tested. The tin tetrachloride catalyzed HC phase is as stable as the original aluminum trichloride catalyzed HC phases, and much more stable than the bench mark acid stable commercial phase.