共查询到19条相似文献,搜索用时 125 毫秒
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采用溶胶-凝胶技术制备了丁基胺丙基硅胶毛细管整体柱,此整体固定相表面同时含有能产生阳极的电渗流的仲胺官能团和产生疏水作用的正丁基和丙基官能团。对所制备的整体柱电色谱性能进行了详细的表征和分析。考察了流动相pH值对电渗流的影响;对烷基苯同系物、有机酸酸性化合物和苯胺类碱性化合物保留行为进行了研究,并对其可能的保留机理进行了探讨。实验结果表明,对于中性化合物的保留机理主要基于反相作用;而对于酸性化合物的保留行为则是基于混合模式作用机理,即除了电泳作用外,还包括阴离子交换和疏水作用。碱性化合物在丁基胺丙基硅胶毛细管整体柱上的峰形较好,没有明显的峰拖尾现象。 相似文献
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建立了低电渗流的毛细管区带电泳分离丹酰氨基酸的新方法,详细研究了缓冲体系的浓度,pH值以及各种添加剂的影响。发现组分迁移时间对缓冲体系pH值极为敏感;添加一定量的甘氨酸,使分离选择性极大的改善;即,能改善待测组分的电离平衡的因素均能有效地改善分离选择性,对低电渗流区带电泳分离机制进行了详尽的讨论。 相似文献
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采用温和条件下的溶胶-凝胶技术,成功制备了阴离子交换-反相混合模式硅胶基质毛细管电色谱整体柱。通过调整反应液中不同前体的比例,优化了整体柱的制备条件。通过扫瞄电镜,对柱床进行了表征和分析。实验发现,所制备的整体柱电渗流的方向和大小可随流动相pH值的改变而改变,在酸性和中性条件下,具有从阴极流向阳极的电渗流;当流动相pH值升至约7.5时,电渗流方向发生了反转(由阳极流向阴极)。在优化的实验条件下,用所制备的整体柱对所考察的酸性(中性)化合物实现了快速分离,并获得了高达160,000N/m的柱效。 相似文献
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在毛细管电泳仪上对12种β-受体阻滞剂和类似物的光学对映体进行了分离,研究了它们的拆分条件。使用0.1 mol/L, pH 3.0的磷酸-三乙醇胺缓冲液,20 kV电压,12~36 mmol/L羟丙基-β-环糊精作为手性识别试剂。其中11 种β-受体阻滞剂及其类似物以及苯乙醇胺、胺酵素在50 cm普通毛细管上获得了较好的手性分离效果,普罗勒沙的对映体在本条件下未获分离。同时发现,芳香环上取代基位置对迁移时间的影响有一定规律。 相似文献
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Lepri等首先用离子对技术研究了18种水溶性食品染料在氯化十二烷基吡啶浸渍的硅烷化硅胶薄层板上的色谱行为.随后Ruijten指出,离子对反相色谱技术对手芳香化合物和脂肪化合物中离解基团的鉴定是一种有效的手段,化合物中的R值与分子中各种基团(羧酸基、磺酸基、胺基等)数目和位置相关。在染料分子中多含有磺酸基、羧酸基或伯、仲、叔的胺基。因而,离子对反相色谱技术对它们的分离特别有用。我们曾用苯基键合板以溴化四丁基胺为反离子,成功地分离了四种酸性食品染料。本文用甲基苯乙基二氯硅烷与硅胶G预涂板反应,制备了一种新的键合板,用于分离碱性染料效果良好。 相似文献
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β—受体阻滞剂及其类似物的毛细管电泳手性分离 总被引:1,自引:0,他引:1
在毛细管电泳上对12种β-受体阻滞剂和类似物的光学对映体进行了分离,研究了它们的拆分条件。使用0.1mol/L,pH3.0的磷酸-三乙醇胺缓冲液,20kV电压,12-36mmol/L羟丙基-β-环糊精作为手性识别试剂。其中11种β-受体阻滞剂及其类似物以苯乙醇胺、胺酵素在50cm普通毛细管上获得了较好的手性分离效果,普罗勒沙的对映体在本条件下未获分离。同时发现,芳香环上取代基位置对迁移时间的影响有一定规律。 相似文献
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设计并合成了一种适用于酸性条件的新型pH荧光探针2,8-双((E)-2-(吡啶-3-基)乙烯基)-6H,12H-5,11-甲二苯并[b,f] [1,5]重氮(TBMP)。探针TBMP以朝格尔碱为骨架,两翼引入间位取代的吡啶端基,其结构经1H NMR、 13C NMR和HR-MS(ESI)表征。并利用pH滴定实验和DFT理论计算探索了探针的pH值变化响应机理。结果表明:探针TBMP由于其间位取代的取代位置效应,显示出独特的两步质子化过程以及特殊的紫外和荧光响应。此外,该探针可以有效地探测酸性pH值(6.5~3.11),并具有良好的稳定性、选择性和较大的斯托克斯位移(127 nm)。 相似文献
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A fast, convenient and sensitive method of capillary zone electrophoresis (CZE) and indirect UV detection was proposed for the determination of 16 amino acids. p-Aminobenzoic acid (PAB) was selected as a background electrolyte (BGE). An isolated cell included a BGE buffer part and an electrode buffer one, which were jointed with a glass frit. The isolated cell can prevent PAB from the electrode reaction and improve the stability of the detection baseline. The separation conditions of amino acids were investigated, such as different BGEs, BGE concentration, buffer pH and electroosmotic flow (EOF) modifiers. Under the selected separation conditions, 14 amino acid peaks could be separated in 12 min. The detection limits of the amino acids were in the range of 1.7 - 4.5 micromol/L. The isolated cell is suitable for reagents reacting on the electrodes in capillary electrophoresis. The proposed method has been successfully applied to the determination of the amino acids in tobacco samples. 相似文献
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Capillary zone electrophoretic (CZE) separations and mass spectrometric analysis of salmon calcitonin and related analogues were performed to generate electrophoresis and mass fingerprints for quality control of the recombinant polypeptide pharmaceutical salmon calcitonin. The calcitonins and their corresponding tryptic digests were successfully separated by CZE at low pH in fused silica capillaries dynamically modified with poly-cationic polymers. The poly-cationic modified inner surface of the fused silica capillaries generated a strong anionic electroosmotic flow (EOF). Analytes of negative, neutral, and positive charge were all swept through the capillary toward the positive electrode. Compared to Polybrene-coated capillaries, capillaries coated with PEI showed a markedly slower but much more stable electroosmotic flow. The migration order of the analytes was predicted by comparing approximate values of the charge to (molecular mass)2/3 ratios. The predicted migration order was confirmed by off-line analysis of CZE fractions with matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). 相似文献
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Applications of a sulfonated-polymer wall-modified open-tubular fused-silica capillary in capillary zone electrophoretic separations 总被引:1,自引:0,他引:1
A fused-silica capillary that is wall-modified via chemically bonding a sulfonated polymer to the capillary wall has a uniform negative charge density on its surface and produces an electroosmotic flow (EOF) greater than 4 x 10(-4) cm2 V(-1) s(-1) The EOF is nearly independent of buffer pH over the pH range of 2 to 10 and is lower than the EOF obtained for the bare fused-silica capillary at the more basic pH but is higher at the more acidic buffer pH. Optimization of buffer pH can be based on analyte pKa values to improve the overall quality of the capillary zone electrophoresis (CZE) separation of complex mixtures of weak acid and base analytes. Because of the high EOF in an acidic buffer, the capillary is useful for the separation of weak organic bases which are in their cation forms in the acidic buffer. EOF for the sulfonic acid bonded phase capillary can be adjusted via buffer additives such as organic solvent, tetraalkylammonium salts, multivalent cations and alkylsulfonic acids. The advantages of utilizing buffer pH and the EOF buffer modifiers to enhance migration time, selectivity, and resolution in CZE separations with this capillary are illustrated using a series of test analyte mixtures of inorganic anions, carboxylic acids, alkylsulfonic acids, benzenesulfonic acids, sulfas, pyridines, anilines or small-chain peptides. 相似文献
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Run Juan Xu Claire Vidal-Madjar Bernard Sbille Jose Carlos Diez-Masa 《Journal of chromatography. A》1996,730(1-2):289-295
Capillary zone electrophoretic (CZE) separation of basic proteins has been achieved with capillary columns modified with copolymers of vinylpyrrolidone (VP) and vinylimidazole (VI). The copolymerization reaction is performed inside the capillary column and involves chemical bonding of the polymer to silica. The electroosmotic flow (EOF) is greatly decreased by this surface modification. The presence of positive charges on the coating surface, due to the cationic property of vinylimidazole at pH below 7, reduces the adsorption of basic proteins onto the silanol groups of the capillary surface. Acidic proteins are irreversibly adsorbed, but rapid separation and good performance reproducibility are obtained with basic proteins. In the case of capillaries modified with VP, the acidic and basic proteins are eluted within 10 min. In this work, we studied the effects of pH and buffer concentration on the magnitude of the EOF, as well as the effect of copolymer composition on the separation efficiency. 相似文献
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To obtain reproducible migration times and rapid analyses of analytes, sulfonate groups were chemically introduced to the inner wall of untreated fused-silica capillary with 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane. The sulfonated capillary showed relatively constant electroosmotic mobility which was greater than that obtained by an untreated fused-silica capillary over the pH range studied (pH 2-9). In both CZE and MEKC, the RSDs of the migration times of analytes with the sulfonated capillary were less than 0.2% which were significantly lower than those obtained with an untreated fused-silica capillary (0.5-3.5%). When BGE were set at pH 7.0 for CZE and MEKC, the analysis times with the sulfonated capillary were about half those obtained with an untreated fused-silica capillary. These results indicate that the sulfonated capillary can provide highly reproducible and rapid analyses in CE. 相似文献
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A surface modification has been developed which yields fused silica capillaries with switchable electroosmotic flow (anodal/cathodal). The capillary surface is a composite material consisting of unreacted silanol groups, a layer of positively charged quaternary ammonium functions, and a hydrophilic layer of long polyether chains. Because of the presence of positively and negatively charged groups, the net charge of the capillary surface can be varied from positive to negative by changing the pH of the running electrolyte, thus enabling manipulation of the magnitude and direction of the electroosmotic flow. The long polyether chains were effective in shielding biomacromolecules from the charged inner surface of the capillary, thus minimizing electrostatic interaction of the solutes with both unreacted silanols and the quaternary ammonium groups which had been introduced. As a consequence, high separation efficiencies were achieved with proteins, nucleotides, and a series of acidic oligosaccharides. 相似文献
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A silica-based CEC monolithic column with mixed modes of RP and weak anion-exchange (WAX) was successfully prepared by using the sol-gel technique at mild temperature. The synthesizing procedure was optimized by changing the ratios of tetraethoxysilane (TEOS), aminopropyltriethoxysilane (APTES), and octyltriethoxysilane (C(8)-TEOS) in the mixture. While serving as WAX group, the amino group dominated the charge on the surface of the capillary column and generated an EOF from cathode to anode at low pH. At pH above 7.5, a cathodic EOF was observed due to the full ionization of silanol group and the suppression in the ionization of amino group. The morphology of monolithic columns was examined by SEM, and the performance of column was evaluated in detail by separating different kinds of compounds. As expected, the monolithic column exhibited RP chromatographic behavior for neutral solutes. Fast and efficient separation of six aromatic acids was obtained using acidic mobile phase with column efficiency up to 160,000 plates/m. Symmetrical peaks can be obtained for aromatic amines because positively charged amino groups on the surface can effectively minimize the adsorption of positively charged analytes to the stationary phase. 相似文献
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In order to accomplish the analysis of peptides and proteins by capillary electrophoresis, Lupamin, a high-molecular-weight linear polyvinylamine (PVAm) polymer, was introduced to modify the inner wall of fused-silica capillaries by physical absorption. Thanks to the high density of positively charged amino groups in Lupamin under acidic conditions, not only is a strong reversed electroosmotic flow generated in the coated capillary but the adsorption of analytes on the inner wall of the capillary is also efficiently eliminated. It has been demonstrated that the Lupamin-coated capillary can be used to advantage for the rapid analysis of amino acids, peptides, and proteins with good resolution and peak shape by capillary electrophoresis. In order to evaluate the basic feature of a Lupamin-coated capillary, electroosmotic flows generated by a Lupamin coating layer under different conditions including pH, coating time, concentration, and the composition of electrolytes on Lupamin-coated and uncoated capillaries were investigated. Furthermore, electrospray ionization-mass spectrometry (ESI-MS) detection was carried out for the analysis of amino acids and peptides. 相似文献