基于无接触电导检测和流动注射进样的微型毛细管电泳系统

毛细管电泳(CE)电导检测(CD)是相对较灵敏和仪器结构简单的一项溶液分析技术,尤其是对于无生色团的无机离子分析更具有突出优势.然而,目前众多商品CE仪器并不配置CD检测器,这极大地限制了该项技术的发展.     

毛细管电泳及芯片毛细管电泳的电容耦合非接触电导检测

综述了毛细管电泳(CE)及芯片毛细管电泳(MCE)的电容耦合非接触电导检测(Capacitively Coupled Contactless Conductivity detection,C4D)的研究状况;并分别对其装置、检测的影响因素及其应用进行了评述。引用文献81篇。     

2015年毛细管电泳技术年度回顾

本文为2015年毛细管电泳(CE)技术的年度回顾。归纳了ISI Web of Science中检索的2015年度CE技术相关的论文,从毛细管电泳-质谱(CE-MS)联用技术、方法学研究、检测与富集、手性分子拆分及CE技术应用5个方面进行了分类说明;简要介绍了2015年涉及CE技术的国际会议6个,国内会议2个以及各会议的研究报道情况。最后,介绍了目前国内外的单克隆抗体、水质、酒类和食品分析中涉及的毛细管电泳的方法标准。     

基于USB技术的毛细管电泳仪的改进

高效毛细管电泳(HPCE)具有进样量少、绝对灵敏度高、分辨率高等特点,在生命科学、医学、化工、药物分析、食品、环境保护等领域得到广泛应用。1987年Ewing首次将电化学检测技术(EC)用于毛细管电泳(CE),克服了光学检测光程短、灵敏度不高的缺点,具有广泛的应用前景[1-2]。本工作     

高效毛细管电泳在核酸、蛋白质分析中的新进展

高效毛细管电泳以其分离效率高，分析速度快，样品和试剂用量少，易于实现自动化等优点，在核酸、蛋白质等生物样品的分析方面发挥着重要的作用并具有巨大的潜力。本文介绍了近两年来高效毛细管电泳技术的进展，特别是PCR／CE、CE／MS以及电泳芯片技术等方面的新发展，并综述了高效毛细管电泳在核酸、蛋白质分析方面的应用，同时对其前景进行了展望。     

新型微型电导池的研制及共地效应的消除

使用简便的方法制作了电极面积大、无死体积、分辨率高、检测限低的微型电导池;较好地消除了毛细管电泳(CE)在柱电导检测装置中存在的共地效应,排除了在线检测时高压分离回路对电导检测回路的干扰.并对制作的微型电导池的性能进行了测试.     

一种组装的毛细管电泳系统

毛细管电泳(Capillary Electrophoresis,CE)作为一种新兴的高效快速分离分析技术近年来发展极为迅速,国外已经有多种CE整机实现了商品化,并开始进入中国市场。这些CE仪器各具特色,应用也非常成功。但对于国内用户来说,价格显然太     

大通道毛细管电泳技术的研究进展

毛细管电泳(Capillary Electrophoresis,CE)在痕量物质的分析与检测、样品的半制备与制备、多维分析以及联用技术中仍面临巨大挑战,研究者从降低电场强度、使用低电导率缓冲液、加入有机试剂、引入制冷,发展了毛细管内径大于150 μm的大通道毛细管电泳技术(Wide-bore Electrophoresis,WBE).本文综述了这一新型大通道毛细管电泳及其相关的多维和联用技术,展望了WBE的发展趋势及潜在应用.     

毛细管电泳在毒品分析中的应用

综述了近年来毛细管电泳(CE)在毒品分析中的应用进展,介绍了不同的CE模式并给出了应用实例,展望了CE在毒品分析中的应用前景.     

毛细管电泳非接触电导检测技术的新发展

毛细管电泳非接触电导检测(CE-CCD)是近年来发展迅速的一种检测技术。本文介绍了非接触式电导检测(CCD)的发展概况,着重阐述了CCD的原理、组成及应用情况。     

Carbon nanotube-enhanced separation of DNA fragments by a portable capillary electrophoresis system with contactless conductivity detection

It was demonstrated that separation of DNA fragments by a CE-contactless conductivity detection system (CE-CCD) could be enhanced with multiple-wall carbon nanotubes (MWCNs) as buffer additive. For HaeIII digest of PhiX174 DNA, optimized MWCN concentration was obtained when the MWCN was above its threshold concentration, at which MWCN could form a network in the buffer as pseudostationary phase to provide additional interaction sites. In the case of larger DNA, MWCN near or below its threshold concentration was enough to provide great improvement of the resolution, which was shown by the separation of the 2-Log DNA ladder. Furthermore, the buffer containing MWCN could provide a more stable baseline in the CE-CCD system, owing to less fluctuation of its conductivity. Compared with CE-UV, CE-CCD with MWCN could provide lower LODs as well as better resolution.     

Simultaneous determination of low-molecular-weight organic acids and chlorinated acid herbicides in environmental water by a portable CE system with contactless conductivity detection

This report describes a method to simultaneously determine 11 low-molecular-weight (LMW) organic acids and 16 chlorinated acid herbicides within a single run by a portable CE system with contactless conductivity detection (CCD) in a poly(vinyl alcohol) (PVA)-coated capillary. Under the optimized condition, the LODs of CE-CCD ranged from 0.056 to 0.270 ppm, which were better than for indirect UV (IUV) detection of the 11 LMW organic acids or UV detection of the 16 chlorinated acid herbicides. Combined with an on-line field-amplified sample stacking (FASS) procedure, sensitivity enhancement of 632- to 1078-fold was achieved, with satisfactory reproducibility (RSDs of migration times less than 2.2%, and RSDs of peak areas less than 5.1%). The FASS-CE-CCD method was successfully applied to determine the two groups of acidic pollutants in two kinds of environmental water samples. The portable CE-CCD system shows advantages such as simplicity, cost effectiveness, and miniaturization. Therefore, the method presented in this report has great potential for onsite analysis of various pollutants at the trace level.     

Highly sensitive chemiluminescence detection of copper(II) in capillary electrophoresis with field-amplified sample injection

Field-amplified sample injection of copper(II) was investigated using capillary electrophoresis with chemiluminescence detection. The sensitivity of copper(II) has been improved markedly by the field-amplified sample injection technique and the detection limit reaches 2 x 10(-11) M. By injection of a short plug of water before sample introduction, the sensitivity can be further improved 5-fold and the detection limit reaches 4 x 10(-12) M. The relative standard deviations (n = 6) of the migration time and the peak height are 0.61% and 4.7% at 1.0 x 10(-9) M Cu(II), respectively. Parameters affecting the field-amplified sample injection, such as separation voltage and concentration of electrophoretic buffer, have been investigated.     

Quantitation and on-line concentration of enantiomers in open-tubular capillary electrochromatography.

The feasibility of open-tubular capillary electrochromatography (OTCEC) with UV detector for quantitation of enantiomers is explored, and a simple on-line sample concentration method to improve detection sensitivity of negatively charged enantiomers more than 1000-fold is described. With a capillary of 25 microm ID, the limits of detection (LODs) for absolute concentration and for enantiomeric ratio are 10(-6) M and 0.6-0.8% (signal-to-noise ratio S/N = 10). Good linearity and reproducibility are observed. The detection sensitivity is enhanced by combination with field-enhanced sample injection (FESI). A water plug is introduced hydrodynamically into the capillary inlet end and then the sample solution prepared with water is introduced with electrokinetic injection. With this concentration technique, the LOD for absolute concentration is reduced to a 10(-9) M level. On the other hand, due to the peak-sharpening effect of FESI, the LOD for enantiomeric ratio for the first-eluted enantiomer is significantly improved, being 0.3%. Effects of the injection conditions, such as length of water plug, buffer concentration, injection voltage, and injection time on the enrichment efficiency are investigated. Online concentration of a racemic compound with two chiral centers is demonstrated.     

An overview on flow methods for the chemiluminescence determination of phosphorus

A review on the flow analysis of phosphorus with chemiluminescence detection is presented. A brief discussion of the chemiluminescence principles and applications is given. Particular emphasis is devoted to coupling different flow techniques (flow injection, sequential injection, multicommutation, multisyringe flow injection, multi-pumping) to chemiluminescence detection. Enzymatic and non-enzymatic methods, mostly applied to environmental samples, are summarized and compared in terms of application range, detection limits, flow configuration, repeatability and sampling rate.     

Peroxyoxalate chemiluminescence detection of condensates of malondialdehyde with thiobarbituric acids using a flow system.

The peroxyoxalate chemiluminescence(CL) detection method for the evaluation of the CL intensity of malondialdehyde(MDA) condensates with seven 2-thiobarbituric acid derivatives is described. The method consists of a flow injection technique together with a CL detection system using bis(2,4,6-trichlorophenyl) oxalate(TCPO) and hydrogen peroxide as chemiluminogenic reagents. Linear correlations between CL intensity and concentration are obtained for pmol levels of condensates. Among the condensates, 1,3-diethyl-2-thiobarbituric acid(DETBA)-MDA shows the largest CL intensity. High performance liquid chromatography (HPLC)/CL detection of DETBA-MDA and 1,3-diphenyl-2-thiobarbituric acid(DPTBA)-MDA using a mixture of TCPO and hydrogen peroxide in acetonitrile as a postcolumn reagent solution is also described. The detection limits for DETBA-MDA and DPTBA-MDA are 20 and 200 fmol, respectively, per 20 microL injection at a signal-to-noise ratio of 2. This HPLC/CL detection system was applied to the determination of MDA in rat brains by using DETBA as a fluorescent derivatizing reagent.     

Multiplexed detection of nitrate and nitrite for capillary electrophoresis with an automated device for high injection efficiency

A simple automated nanoliter scale injection device which allows for reproducible 5 nL sample injections from samples with a volume of <1 microL is successfully used for conventional capillary electrophoresis (CE) and Hadamard transform (HT) CE detection. Two standard fused silica capillaries are assembled axially through the device to function as an injection and a separation capillary. Sample solution is supplied to the injection capillary using pressure controlled with a solenoid valve. Buffer solution flows gravimetrically by the junction of the injection and separation capillaries and is also gated with a solenoid valve. Plugs of sample are pushed into the space between the injection and separation capillaries for electrokinectic injection. To evaluate the performance of the injection device, several optimizations are performed including the influence of flow rates, the injected sample volume and the control of the buffer transverse flow on the overall sensitivity. The system was then applied to HT-CE-UV detection for the signal-to-noise ratio (S/N) improvement of the nitric oxide (NO) metabolites, nitrite and nitrate. In addition, signal averaging was performed to explore the possibility of greater sensitivity enhancements compared to single injections.     

Determination of hydrolytic degradation products of nerve agents by injection port fluorination in gas chromatography/mass spectrometry for the verification of the Chemical Weapons Convention

Retrospective detection and identification of markers of chemical warfare agents are important aspects of verification of the Chemical Weapons Convention. Alkyl alkylphosphonic acids (AAPAs) and alkylphosphonic acids (APAs) are important markers of nerve agents. We describe the development and optimization of a new gas chromatography/mass spectrometry (GC/MS) injection port fluorination method for the derivatization of AAPAs and APAs. The process involved the injection of acids with trifluoroacetic anhydride in GC/MS, where acids are converted into their corresponding volatile fluorides. Various reaction conditions such as fluorinating agent, injection port temperature and splitless time were optimized. The maximum reaction efficiency of the acids with trifluoroacetic anhydride was observed at 230 degrees C injection port temperature with a splitless time of 2 min. APAs showed best analytical efficiencies at 400 degrees C injection port temperature, while the other conditions were similar to those of AAPAs. The linearities of response for APAs and AAPAs were in the range of 1-25 and 5-100 microg mL(-1), respectively, with limits of detection ranging from 500 pg to 800 ng mL(-1).     

Determination of environmentally relevant aromatic amines in the ppt levels by cation selective exhaustive injection-sweeping-micellar electrokinetic chromatography

Environmentally important aromatic amines are determined by micellar electrokinetic chromatography (MEKC) with UV detection. Using a combination of field-enhanced sample injection in the capillary zone electrophoresis format (performed for a longer period than usual, e.g., 200 s at high voltages; cation selective exhaustive injection) and sweeping in the MEKC format, from 10(4)- to 10(5)-fold improvements in detector response are achieved for all positively chargeable test analytes. Preliminary results indicate that limits of detection for the positively chargeable aromatic amines are in the parts per trillion (ppt) levels.     

Critical aspects of the determination of pentafluorobenzyl derivatives of aldehydes by gas chromatography with electron-capture or mass spectrometric detection: Validation of an optimized strategy for the determination of oxygen-related odor-active aldehydes in wine

This work presents a thorough study of some aspects critical to the quantitative performance of methods for the determination of volatile aldehydes previously derivatized to pentafluorobenzyl hydroxylamine oximes. The conclusions of the study are further applied to the validation of an optimized procedure for the determination of oxidation-related aldehydes from wine. Aspects studied include the chromatographic injection, the analytical performance of electron-capture detection (ECD) or MS detection, and the way in which the derivatization is carried out. Different injection techniques have been optimized and compared (classical splitless-hot injection; cold splitless; and large volume solvent split injection). All of them were carried out in a programmed temperature vaporization (PTV) injector, with a 350 microL internal volume liner (3.4 mm internal diameter). Classical splitless injection of hexane extracts is troublesome and requires large carrier gas flows (>10 mL min(-1)). Cold splitless injection was clearly superior. Large volume solvent split injection has been also optimized. ECD has been found to lack the necessary selectivity for the determination of unsaturated aldehydes in wine, although the quantitation of several minor aldehydes is possible. MS detection has proven to be superior for the determination of these compounds in wine. The way in which the reagent is applied is also critical and for the case of wine is important to ensure that the reagent is applied after some of the major wine aldehydes have been eliminated. The finally proposed method is extremely sensitive. Method detection limits ranged from 0.002 microg L(-1) (for unsaturated aldehydes) to 0.73 microg L(-1) (for phenylacetaldehyde) and precision (measured as relative standard deviation) is < or =6% in all cases. The method makes it possible to determine quantitatively in a single run the wine aldehydes with sensory significance (isobutyraldehyde, 2-methylbutanal, isovaleraldehyde, (E)-2-hexenal, (E)-2-heptenal, (E)-2-octenal, (E)-2-nonenal, methional and phenylacetaldehyde).