共查询到20条相似文献,搜索用时 578 毫秒
1.
2.
3.
4.
单级高压微流量电渗泵的研究 总被引:1,自引:0,他引:1
设计了一种高压微流量电渗泵。泵体主要由高压电源、电渗柱、毛细通道、导电空心电极以及气泡去除器、压力传感器等构成。单级电渗泵可以给出0~20MPa范围的输出压力和nL~μL级输出流量。输出压强和输出流量取决于电压、填充柱阻力和流体性质。 相似文献
5.
在75μm×20cm的毛细管ODS填充柱上实现毛细管反相电色谱分离,考察种种分离因素,包括流动相的组成,有机相的种类和比例,电解质缓冲液的种类浓度和PH值,以及分离电压和分离温度等因素对填充毛细管电渗流的影响,系统研究了反相毛细管电色谱的电渗变化规律。 相似文献
6.
温度和缓冲溶液对胶束电动毛细管色谱的迁移时间窗口的影响 总被引:1,自引:0,他引:1
以电渗淌度、胶束电泳淌度和淌度比这3个参数为考察对象,研究了毛细管温度、缓冲溶液种类和浓度对胶束电动毛细管色谱的迁移时间窗口的影响。电渗淌度和胶束电泳淌度均随毛细管温度的升高线性的增加,粘度是这一影响中的主要因素。理论上证明了管壁表面的局部粘度与主体粘度不同。当温度变化时,电渗淌度和胶束电泳淌度的变化幅度不同。降低温度可以扩展迁移时间窗口,虽然扩展幅度较小,但在商品化仪器上易于实现。推导出能统一描述电渗淌度和胶束电泳淌度与缓冲溶液浓度间的关系式。 相似文献
7.
通过将聚谷氨酸苄酯(PBLG)掺杂在硅胶中,建立了一种分离手性物质氧氟沙星对映体的方法。以壳聚糖为引发剂,利用开环聚合方法合成了PBLG。将PBLG掺杂在硅胶G中制备薄层色谱板,实现了对氧氟沙星外消旋体的拆分。考察了展开溶剂体系、不同比例溶剂、展开温度和展开时间对手性拆分氧氟沙星对映异构体的影响。结果表明,该薄层色谱板拆分氧氟沙星对映异构体的最佳条件为:0.5 g PBLG掺杂在2 g硅胶G中,以乙腈-甲醇(V/V=2∶1)混合溶剂为展开体系,35℃下展开30 min。氧氟沙星对映体单体在薄层色谱板上的手性分离因子(α)范围为2.62~6.12,实现了基线分离。 相似文献
8.
圆周薄层色谱能将样品展开为很细的谱线,具有较高的分辨能力,常用于分析一些难分离的物质。这种色谱方法过去只能采用水平展开方法。我们将普通薄层板修饰成特定形状,用最常见的上行展开法获得近似于圆周薄层的色谱。方法不需要特殊展开装置,应用于皂苷、生物碱的分离鉴定取得很好效果。 相似文献
9.
基于对电渗泵中压强产生原理的讨论, 对新兴的复杂串、并联电渗泵系统的流体输液特征加以研究. 在多级串联电渗泵系统中, 可以通过增加电渗泵的级数或操作电压来提高泵系统产生的压强, 但是单一流路的输液能力有限. 而在多级并联电渗泵系统中, 输液量也可以通过增加电渗泵的级数或操作电压得到提高. 在这一体系中, 尽管输液量的叠加有利于其在更为广泛的领域中应用, 但是因Joule热产生的电场强度与电渗流速度线性关系的偏离也使得其线性范围变小, 不利于操作条件的控制. 相似文献
10.
吸附蛋白质固定相电色谱手性分离的研究 总被引:5,自引:1,他引:4
将牛血清白蛋白 (BSA)吸附于强阴离子交换固定相 (SAX)上用于电色谱手性分离。当SAX吸附BSA后 ,电渗淌度仅仅下降 2 6 3% ,而电渗流的方向没有改变。在该系统中电渗流的方向和阴离子的电泳方向一致 ,因而克服了一般蛋白质固定相不能分离酸性对映体的缺点。 1种中性对映体安息香和 4种阴离子性对映体色氨酸、华法令、非诺洛芬、酮基布洛芬获得了成功分离。当流动相含体积分数为 7%的乙腈时 ,死时间和D 色氨酸、L 色氨酸的迁移时间的相对标准偏差分别为 0 90 % ,0 87%和 0 96 % (n =2 1) ,说明该体系有很好的重现性。 相似文献
11.
12.
13.
The N-chamber, the most often in the method of thin-layer chromatography (TLC) for the separation, is used with the previous process of equilibrium saturation of the TLC plate with the mobile phase (MP) vapors, what, unfortunately, requires about 1 h. For the acceleration of the processes of saturation of the analytical plate with the vapors of the mobile phase, the use of a specially developed N-chamber of the new type containing a specific cassette holder has been proposed. In this cassette holder, a feeding plate (that is a TLC plate, previously wetted by MP) was additionally placed parallel to the analytical plate at a very small distance (0.2–1.0 mm). In these conditions, the process of saturation of the analytical plate with the MP vapors is accelerated substantially, and it passes with the improved repeatability. The new approach permitted to substantially (up to 2 times) decrease the time necessary for the TLC plate development in the N-chamber. 相似文献
14.
Separation of ephedrine stereoisomers by molecularly imprinted polymers was performed to study the factors that affect the selectivity and column efficiency. The polymer synthesized with pentaerythritol triacrylate as the cross-linker and chloroform as the porogen was found to have the best overall separation performance. Investigation of the recognition mechanism by NMR and chromatographic analysis revealed that the major binding forces between the polymer stationary phase and ephedrine are the ionic and hydrogen bonding interactions. Studies of the influence of mobile phase compositions on the HPLC analysis have shown that a methanol-aqueous buffer was the suitable mobile phase for the separation in which pH, ionic strength and water content can be adjusted to optimize the chromatographic analysis. 相似文献
15.
A new hydrophobic interaction HPLC column is used for the rapid purification of proteinase inhibitors isolated from arrowhead. The inhibitors, partially purified by DEAE-cellulose column chromatography, are resolved into three components with a mobile phase gradient of decreasing salt concentration from 1.1 M ammonium sulfate in 0.01 M phosphate buffer to phosphate buffer alone. This new HPLC column is found to be very useful for rapid, semipreparative purification of hydrophobic protein and sample loading of up to 1.6 mg of inhibitors can be fully resolved on an analytical column. 相似文献
16.
Summary The particle realization of electrochromatography on capillaries packed with 1.5 μm ODS-modified non-porous silica spheres
is demonstrated. In order to realize stable separation conditions it is crucial to add sodium dodecylsulphate (SDS) to the
mobile phase and to pressurize both buffer vials at 10 bar. The presence of SDS stabilizes the current and makes the electro-osmotic
flow in the packing more uniform so that no air bubbles are generated at high field strengths. The capillary columns are extremely
efficient and on a 24 cm long column about 120,000 plates can be generated (a reduced plate height of about 1.3). The columns
are very stable and no loss in efficiency was found after using a column continuously for two months. 相似文献
17.
Statistical theory for hydrogen bonding fluid system of A_aD_d type (I): The geometrical phase transition 总被引:2,自引:2,他引:0
WANG Haijun HONG Xiaozhong GU Fang & BA Xinwu . College of Chemistry Environment Science Hebei University Baoding China . International Center for Materials Physics Chinese Academy of Sciences Shenyang China . College of Physics Science Technology Hebei University Baoding China 《中国科学B辑(英文版)》2006,49(6)
The influence of hydrogen bonds on the physical and chemical properties of hydrogen bonding fluid system of AaDd type is investigated from two viewpoints by the principle of statistical mechanics. In detail, we proposed two new ways that can be used to obtain the equilibrium size distribution of the hydrogen bonding clusters, and derived the analytical expression of a relationship between the hydrogen bonding free energy and hydrogen bonding degree. For the nonlinear hydrogen bonding systems, it is shown that the sol-gel phase transition can take place under proper conditions, which is further proven to be a kind of geometrical phase transition rather than a thermodynamic one. Moreover, several problems associated with the geometrical phase transition and liquid-solid phase transition in nonlinear hydrogen bonding systems are discussed. 相似文献
18.
19.
The use of methanol-aqueous buffer mobile phases in HPLC is a common election when performing chromatographic separations of ionisable analytes. The addition of methanol to the aqueous buffer to prepare such a mobile phase changes the buffer capacity and the pH of the solution. In the present work, the variation of these buffer properties is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-hydrogencitrate-citrate, and ammonium-ammonia buffers. It is well established that the pH change of the buffers depends on the initial concentration and aqueous pH of the buffer, on the percentage of methanol added, and on the particular buffer used. The proposed equations allow the pH estimation of methanol-water buffered mobile phases up to 80% in volume of organic modifier from initial aqueous buffer pH and buffer concentration (before adding methanol) between 0.001 and 0.01 mol L(-1). From both the estimated pH values of the mobile phase and the estimated pKa of the ionisable analytes, it is possible to predict the degree of ionisation of the analytes and therefore, the interpretation of acid-base analytes behaviour in a particular methanol-water buffered mobile phase. 相似文献
20.
The influence of hydrogen bonds on the physical and chemical properties of hydrogen bonding fluid system of A a D d type is investigated from two viewpoints by the principle of statistical mechanics. In detail, we proposed two new ways that can be used to obtain the equilibrium size distribution of the hydrogen bonding clusters, and derived the analytical expression of a relationship between the hydrogen bonding free energy and hydrogen bonding degree. For the nonlinear hydrogen bonding systems, it is shown that the sol-gel phase transition can take place under proper conditions, which is further proven to be a kind of geometrical phase transition rather than a thermodynamic one. Moreover, several problems associated with the geometrical phase transition and liquid-solid phase transition in nonlinear hydrogen bonding systems are discussed. 相似文献