毛细管电泳在手性分离中的应用进展

本文以手性选择剂为线索综述了近五年来毛细管区带电泳和胶束电动毛细管电色谱在手性药物拆分中的应用进展,列举了部分手性药物拆分实例.     

毛细管电泳法分析维甲酸异构体

采用毛细管电泳分析方法对维甲酸异构体进行了分离。比较了区带电泳和胶束电动色谱两种模式对维甲酸异构体的分离效果。考察了缓冲液组成、pH值、乙腈含量以及十二烷基硫酸钠(SDS)浓度等对分离的影响。采用胶束电动色谱法可完全分离13-顺-和全反式-维甲酸,最佳的缓冲溶液为(20 mmol/L Tris-H3BO3(pH 8.5)-25 mmol/L SDS)-乙腈(体积比为80∶20)。该法首次应用于加标血浆中的维甲酸分析,获得了较好的结果。     

含双T切换接口的胶束电动色谱-毛细管区带电泳二维电泳芯片上混合氨基酸的分离富集

基于时间顺序设计提出了含双T切换接口的胶束电动色谱(MEKC)和毛细管区带电泳(CZE)的二维芯片,构建了相应的芯片分析测试系统.基于FITC标记的氨基酸样品的一维MEKC和CZE实验结果,对二维进样时间、二维分离启动时间等二维芯片电泳关键操作参数进行了优化.采用所构建的MEKC-CZE二维芯片电泳分析系统对精氨酸、赖氨酸、组氨酸、苯丙氨酸和酪氨酸的混合样品进行了二维芯片电泳分离分析,计算得到两种分离模式的正交性为56.0%.     

毛细管电泳在火炸药分析中的应用

综述了近年来毛细管电泳在火炸药领域的应用现状，包括各种分离模式、检测器以及毛细管电泳芯片的应用，并对该技术在火炸药分析中的应用前景作了展望，提出了新的发展方向。引用文献45篇。     

氨基酸对映体的芯片毛细管电泳拆分

在毛细管电泳芯片上，采用CD－SDS－MEKC模式，对FITC标记的3种氨基酸对映体进行了手性分离研究。CD种类、浓度、SDS浓度以及各种添加剂对氨基酸对映体拆分有影响，认定γ－CD对FITC标记的氨基酸手性识别能力较强，在含有5mmol/L γ-CD和30mmol/L SDSr 10mmol/L,pH10.0的硼砂缓冲溶液中，3种氨基酸对映体得到了较好的分离。     

毛细管区带电泳

一、历史与现状 毛细管区带电泳(CZE)或高效毛细管电泳(RPCE)是继色谱之后的又一高效快速分析方法,近年来发展极快(图1)。CZE的研究热潮正在英国掀起,并向其他国家扩展。CZE是第六届国际等速电泳会议的主题之一,在88年的Pitts-burg会上受到高度重视。其首届专题国际会议也     

二维毛细管区带电泳/胶束电动毛细管色谱分离尿样中的药物及其对映体

建立了毛细管区带电泳(CZE)/胶束电动毛细管色谱(MEKC)二维毛细管电泳分离平台,CZE毛细管和MEKC毛细管通过一段带微孔的聚四氟乙烯(polytetrafluoroethylene, PTFE)套管固定。样品在CZE毛细管中分离后进入MEKC毛细管进一步分离,在二维转换过程中采用动态pH连接-胶束扫集法避免第一维分离区带在接口处扩散。将该方法成功用于鼠尿样品中4种药物及其对映体的分离,各组分的理论塔板数为(2.8～4.3)×104/m,检出限为0.015～0.052 mg/L,实际样品中峰面积和迁移时间的相对标准偏差(n=7)分别为1.7%～3.8%和1.3%～4.6%。方法重现性好、灵敏度和分离度高、峰容量大,适用于尿样中多种药物组分及其对映体的同时分离检测。     

糖类的毛细管电泳及芯片毛细管电泳

 糖类化合物在生物体内发挥多方面的作用。糖研究的复杂性在于其结构的复杂多变。高效毛细管电泳作为一种快速、高效的分离分析手段已广泛应用于糖的研究。芯片毛细管电泳是近几年来发展起来的新的分析技术 ,并已经在生命科学的研究中得到较广泛的应用。就各种糖类化合物的毛细管电泳的分析策略、检测条件及糖类化合物的芯片毛细管电泳进行了阐述 ,共 4 8篇。     

扁形毛细管区带电泳

本文提出用扁形毛细管替代圆形毛细管进行区带电泳,以便解决微孔圆管容量小、光路短,而大孔圆管径向温差大、电泳效率不高的矛盾.从理论和实验两方面对扁、圆两种管的效果进行了比较,证实扁管兼具了微孔圆管和大孔圆管的特长.同时还提出了塑料扁管的制作方法,并研究了此种管的热变形问题.     

糖类的高效毛细管电泳

高效毛细管电泳以其快速、高效、简便、高分辨率、样品和溶剂消耗少及易于仪器化等优点正成为生物活性分子分离和分析工作中的一个重要工具。介绍了作为四大基本生命物质之一的糖类化合物的高效毛细管电泳研究进展，包括CZE、CGE、MECC和CITP等四种分离模式以及直接紫外/荧光法、间接紫外/荧光法、示差法、电化学法和质谱法等五种检测方式。并简要介绍HPCE在单糖、寡糖和多糖分离与分析中的应用，展望了HPCE用于单个细胞中糖类组分的研究前景。     

Optimization of resolution in micellar electrokinetic chromatography

A comparison of separations conducted in sodium dodecyl sulfate (SDS) and SDS modified with Brij 35 indicates that selectivity, in Micellar Electrokinetic Chromatography (MEKC), is governed by the composition of the micellar phase. Beyond selectivity optimization, resolution may be improved by increasing efficiency or decreasing electroosmotic flow. Of these approaches, increasing capillary length (to improve efficiency) should be a more time effective means of improving separation.     

Application of capillary zone electrophoresis to the study of interactions betweenBacillus subtilis tryptophanyl-tRNA synthetase and tRNATrp

Summary The application of capillary zone electrophoresis to the study of interactions betweenBacillus subtilis tryptophanyl-tRNA synthetase (TrpRS) and tRNA^Trp is described. Significant changes in peak shape of tRNA^Trp incubated with TrpRS indicated the occurrence of interactions between TrpRS and tRNA^Trp in pH 8.0 Tris-HCl buffer containing 0.1 mmol L⁻¹ EDTA and 1 mmol L⁻¹−5 mmol L⁻¹ mgCl₂. Addition of Mg²⁺ decreased the electrophoretic mobility of tRNA^Trp, which illustrated that conformation of tRNA^Trp depended on Mg²⁺. The dissociation constant of the TrpRS-tRNA^Trp complex was estimated to be 0.63 μmol L⁻¹ at 25°C in buffer solution.     

Sensitive capillary electrophoresis microchip determination of trinitroaromatic explosives in nonaqueous electrolyte following solid phase extraction

A capillary electrophoresis (CE) microchip is utilized for the sensitive separation and detection of three trinitroaromatic explosives: 1,3,5-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrophenyl-N-methylnitramine (tetryl), in the presence of 10 other explosives and explosive derivatives in nonaqueous electrolyte (acetonitrile/methanol 87.5/12.5 (v/v), 2.5 mM NaOH, 1 mM sodium dodecyl sulfate (SDS)). The chemical reaction of bases, e.g. hydroxide or methoxide ions, with trinitroaromatic compounds forms red colored derivatives that can be easily detected using a green light emitting diode (LED) on the microchip. Two surfactants bearing opposite charge, cetyltrimethylammonium bromide (CTAB) and SDS are compared with respect to their effect on separation times, detection limits and resolving powers for separating these explosives. All microchip separations were achieved in <20 s. In the absence of solid phase extraction (SPE), the detection limits obtained for the trinitroaromatic explosives were as follows: TNB, 60 μg/l; TNT, 160 μg/l and tetryl, 200 μg/l. By coupling the microchip separation with ex situ SPE, the detection limits for detecting these three explosives in seawater were lowered by 240 to more than 1000 times: TNB, 0.25 μg/l; TNT, 0.34 μg/l and tetryl, 0.19 μg/l.     

Analytical study of Joule heating effects on electrokinetic transportation in capillary electrophoresis

Electric fields are often used to transport fluids (by electroosmosis) and separate charged samples (by electrophoresis) in microfluidic devices. However, there exists inevitable Joule heating when electric currents are passing through electrolyte solutions. Joule heating not only increases the fluid temperature, but also produces temperature gradients in cross-stream and axial directions. These temperature effects make fluid properties non-uniform, and hence alter the applied electric potential field and the flow field. The mass species transport is also influenced. In this paper we develop an analytical model to study Joule heating effects on the transport of heat, electricity, momentum and mass species in capillary-based electrophoresis. Close-form formulae are derived for the temperature, applied electrical potential, velocity, and pressure fields at steady state, and the transient concentration field as well. Also available are the compact formulae for the electric current and the volume flow rate through the capillary. It is shown that, due to the thermal end effect, sharp temperature drops appear close to capillary ends, where sharp rises of electric field are required to meet the current continuity. In order to satisfy the mass continuity, pressure gradients have to be induced along the capillary. The resultant curved fluid velocity profile and the increase of molecular diffusion both contribute to the dispersion of samples. However, Joule heating effects enhance the sample transport velocity, reducing the analysis time in capillary electrophoretic separations.     

Stacking and separation of urinary porphyrins in capillary electrophoresis: optimization of concentration efficiency and resolution

We demonstrated that anionic porphyrins could be stacked and separated in micellar electrokinetic chromatography (MEKC) and microemulsion electrokinetic chromatography (MEEKC) by applying acetonitrile and high salt content in human urine sample matrix. The introduction of sample containing acetonitrile and sodium chloride into the CE capillary at more than 10% of the total capillary volume resulted in the improvement of peak resolution and the enhancement of detection sensitivity. The achieved acetonitrile stacking enrichment factors of six porphyrins ranged from 12 to 32 in MEKC and from 28 to 33 in MEEKC, respectively. The stacking technique was successfully applied for analyzing porphyrins present in urine samples that were deproteinized with acetonitrile. For the analysis of coproporphyrin isomers, addition of the sodium cholate (SC) into micelle and microemulsion solutions provided adequate resolution. Calibration curves obtained for the determination of coproporphyrin isomers were found linear between 30 and 400 nmol L⁻¹, and the limit of detection (LOD) was 20 nmol L⁻¹ in MEEKC. Intra- and interday precisions (n = 11) in the microemulsion separation system for the isomers at spiked concentrations of 40-400 nmol L⁻¹ in urine were in the range of 0.1-0.4% and 0.7-7.6% for migration time and peak area, respectively. Coproporphyrin III, coproporphyrin I and uroporphyrin were detected at levels of 80.7 nmol L⁻¹, 32.3 nmol L⁻¹ and 19.8 nmol L⁻¹, respectively, in the urine samples collected from healthy individuals. Different porphyrin profiles, however, were observed in urine samples from porphyria cutanea tarda (PCT) patients.     

A review of pulsed electrochemical detection following liquid chromatography and capillary electrophoresis

Pulsed electrochemical detection (PED) has progressed as a highly sensitive and selective detection technique following aqueous-based separation systems over the past three decades. The application of on-line pulsed potential cleaning to electrocatalytic noble metal electrodes has significantly increased the number of applications formerly achieved with conventional electrochemical (EC) detection. Electrochemical cells are easily miniaturized, providing the ability to apply detection by PED at microelectrodes and onto microchips utilizing electrophoretic separations. In addition, recent advances in PED waveforms and instrumentation have enabled the detection technique to be easily coupled with high pressure separation systems which require rapid detection to maintain separation integrity. As a result, advanced applications for the determination of carbohydrates as well as the expansion of PED for the detection of other organic aliphatic compounds have been recently accomplished. This review will focus on developments and methods utilizing PED following liquid chromatography (LC) and capillary electrophoresis (CE). Publications are reviewed in chronological order to emphasize the advancement of the detection method and the sustained relevance of its applications.     

糖类物质的毛细管电泳分析

毛细管电泳(CE)是近二十年发展起来的一种新的分离分析技术，它以快速、高效、高灵敏度、所需样品少等优点被广泛应用于各个领域。八十年代末开始应用于糖类物质的分析，并获得了快速发展。本文对毛细管电泳分离分析糖类物质进行了评述，主要集中在多糖的水解、衍生、检测、分析应用及前景等方面。全文引用文献40篇。     

Ionic liquids used in and analyzed by capillary and microchip electrophoresis

This review, covering reports published from 2001 to December 2008, shows how ionic liquids (ILs) have made significant contributions in the improvement of capillary and microchip electrophoresis (CE and μCE) for the separation and detection of analytes such as phenols and aromatic acids, metal ions, medicines, enantiomers, biological materials, etc. Furthermore, CE methods applied in the sensitive and accurate determination of physico-chemical properties of ILs have been summarized. Accordingly, research vacancies and future development trends in these areas are discussed.     

Microchip-based capillary electrophoresis for determination of lactate dehydrogenase isoenzymes

This article describes a novel microchip-based capillary electrophoresis and oncolumn enzymatic reaction analysis protocol for lactate dehydrogenase (LDH) isoenzymes with a home-made xenon lamp-induced fluorescence detection system. A microchip integrated with a temperature-control unit is designed and fabricated for low-temperature electrophoretic separation of LDH isoenzymes, optimal enzyme reaction temperature control, and product detection. A four-step operation and temperature control are employed for the determination of LDH activity by on-chip monitoring of the amount of incubation product of NADH during the fixed incubation period and at a fixed temperature. Experiments on the determination of LDH standard sample and serum LDH isoenzymes from a healthy adult donor are carried out. The results are comparable with those obtained by conventional CE. Shorter analysis times and a more stable and lower background baseline can be achieved. The efficient separation of different LDH forms indicates the potential of microfluidic devices for isoenzyme assay.     

Numerical simulation of electrokinetic injection techniques in capillary electrophoresis microchips

The effective design and control of a capillary electrophoresis (CE) microchip requires a thorough understanding of the electrokinetic transport phenomena associated with its microfluidic injection system. The present study utilizes a numerical simulation approach to investigate these electrokinetic transport processes and to study the control parameters of the injection process. Injection systems with a variety of different configurations are designed and tested, including the cross-form, T-form, double-T-form, variable-volume focused flow cross-form, and variable-volume triple-T-form configuration. Each injection system cycles through a predetermined series of steps in which the magnitudes and distributions of the applied electric field are precisely manipulated in order to effectuate a virtual valve. This study investigates the sample leakage effect associated with each of the injection configurations and applies the double-L, pullback, and focusing injection techniques to minimize the sample leakage effect. The injection methods presented in this paper have the exciting potential for use in high-quality, high-throughput chemical analysis applications and throughout the micro-total-analysis systems field.