高效毛细管电泳安培检测器的研制

介绍了一种结构简单的毛细管电泳安培检测器。该检测器通过一只内径与毛细管外径相仿的不锈钢针头作分离毛细管与毛细管工作电极的导引管解决了工作电极与分离毛细管的对接 毛细管碳糊电极为工作电极,在内径为５０μｍ毛线管邮几种酚类化合物,结果表明该系统性能优良。     

几种无机阳离子的毛细管电泳-电容耦合非接触电导分离检测

 研制出电容耦合非接触电导检测器,检测器使用两个5 mm长的管状电极套在分离毛细管的外面,电极相距2 mm并与函数信号发生器连接。对影响检测器检测限和线性范围的激发频率、峰峰电压(V p-p )等因素进行了考察,结果发现频率为25～35 kHz、V p-p 在30 V时检测器有最佳的信号噪声比;以2-N-吗啡啉乙磺酸(MES)-组氨酸(His)为缓冲体系,用自制的检测器对Li+,Na+,K+,Mg 2+ ,Ca 2+ 和Ba 2+ 等几种常见的无机离子进行了毛细管电泳分离检测,优化了缓冲溶液     

毛细管电泳电化学法检测过氧化氢

以金微盘电极和离子液体修饰单壁碳纳米管糊微盘电极分别作为毛细管电泳电化学检测器,试验了两种电极对过氧化氢的响应情况,将金微盘电极与毛细管电泳联用,对过氧化氢进行了定性和定量检测.探讨了分离电压、缓冲溶液pH值和工作电位等条件对H2O2检测的影响.实验结果表明,峰电流与H2O2浓度在1.0×10-6～1.0×10-5mo...     

毛细管的交流阻抗特性研究

采用交流阻抗法研究了电容耦合非接触电导检测池毛细管的阻抗特性,分别考察了电极连接方式和毛细管内径对检测池阻抗的影响.实验表明:高频时,除去毛细管外层保护层会使检测池的阻抗减小,有助于检测器灵敏度的提高;采用铜箔作电极能够有效地消除电极与毛细管壁之间的空隙,使得检测池在低频时阻抗减小.随着毛细管内径的变大,阻抗依次减小.通过Zview软件拟合,提出的简单的拟合等效电路为R(RC)CPE.     

毛细管电泳直立型安培电化学检测器的研究

报道了一种新的用于毛细管电泳检测的直立式微型安培电化学检测器，以束状碳纤维盘状电极为工作电极，分离并测定了儿茶酚胺类物质，平均柱数为２２００００，最小检测量达２５ａｍｏｌ，且结构紧凑，操作简便，易于推广。     

毛细管电泳和火焰光度检测器的联用研究

研究了毛细管电泳与火焰光度检测器的联用技术及其应用。有机磷农药经毛细管电泳分离后，流出液被引入气相色谱的火娄光度检测器进行特效检测，毛细管电泳的接地电极接口采用毛细管裂缝处裹醋酸纤维膜的方法，而毛细管电泳和火焰光度检测器的接口则借用了气相色谱的进样口。     

毛细管电泳多道电化学检测器的研制及其应用

报道了毛细管电泳多道电化学检测器的研制及其应用，安培检测器和电导检测器并联在同一毛细管电泳检测系统中，在同一缓冲体系，同一工作电极下对同一复杂的分析体系同时进行电导和安培检测；整个装置综合了电导检测和安培检测两种检测器的优点，性能优良，造价低廉，对实际样品的检测取得了令人满意的结果。     

毛细管电泳-高频电导法快速测定牡丹皮中的丹皮酚

毛细管电泳—电化学检测的装置简便、价廉、灵敏度高，其中非接触式检测(电极不与溶液直接接触)避免了分离电场对检测的干扰和电极中毒，可广泛用于荷电成分的检测。本文采用本课题组建立的毛细管电泳—非接触高频电导法分析了牡丹皮中的丹皮酚，结果令人满意。     

胶束电动毛细管色谱双通道电化学检测尼群地平

创建了尼群地平的胶束电动毛细管色谱双通道电化学检测的分析新方法。采用 两台安培检测器并联构成双通道检测系统，采用单一碳糊工作电极，两台安培检测 器的检测电位分别设为+0.7V和-0.8V(vs.SCE)同，同时对尼群地平进行氧化和还原 测定，并实时对数据进行采集、处理，以图形方式显示。采用NH3－NH4Cl为背景电 解质，并加入十二烷基硫酸钠（SDS）和甲醇组成运行电泳介质，应用氧化、还原 双通道检测系统对尼群地平及其片剂进行了胶束电动毛细管色谱分离检测；对工作 电极的选择、电极电位的选择、SDS的浓度、甲醇浓度、运行缓冲溶液种类以及工 作电压和进样时间对分离检测的影响进行了研讨，取得满意结果。     

毛细管电泳柱端盘状电极安培检测区带展宽的定量分析

从理论上分析了影响毛细管电泳法端盘状电极安培区检测区带展宽的诸因素，给出了区带展宽的模拟公式，通过实验考察了进样量，分离电压，检测器体体积对区带展宽的影响并验证了模拟公式。     

Improved dual photometric-contactless conductometric detector for capillary electrophoresis

A new design of a dual, UV photometric - contactless conductometric detector is described. The separation capillary with an optical window created is pressed onto two semitubular electrodes, 3 mm wide and 2 mm apart. The electrodes form the detection cell of the contactless conductometric detector. An optical fiber, placed in the gap between the conductometric electrodes, brings radiation from the source. The radiation that passes through the separation capillary is recorded by a large-area photodiode. The optical fiber and the photodiode operate the photometric cell which is between the conductometric electrodes. The detector thus permits simultaneous photometric and conductometric detection in the same place of the capillary, while exchanging of the separation capillary is easy and without effect on the detector geometry and performance.     

Fundamental aspects of contactless conductivity detection for capillary electrophoresis. Part I: Frequency behavior and cell geometry

A better understanding of the characteristics of the axial contactless conductivity cell could be obtained by carefully studying the effect of the cell geometry on its frequency behavior. A good fit between theoretical and experimental results shows that the axial contactless conductometric detector can effectively be described by the simplest possible equivalent circuitry consisting of a capacitor, resistor, and a second capacitor. The cell constant is largely defined by the length of the gap between the electrodes. The effective electrode size is thus not related to the dimensions of the real electrodes but more closely to the cross-sectional area of the internal diameter of the capillary. Typical experimental values of 20 MOmega and 0.1 pF were obtained for the resistance and capacitances, respectively, of a cell formed by a 2 mm gap between two 4 mm long electrodes fitted with a capillary of 50 microm ID. It could be shown that the diameter of the electrode is not critical and tight coupling of the electrodes to the outer wall of the capillary is not needed. The peak overshoot phenomenon, which has frequently been reported, is an artefact that can be minimized by optimizing the frequency for cell excitation. The frequency setting has to be optimized for each cell design, operational amplifier, electrolyte solution and capillary.     

多材料3D打印技术制作用于毛细管电泳的非接触电导/激光诱导荧光二合一检测池

利用多材料3D打印技术研制了用于毛细管电泳(CE)的二合一检测池,实现了电容耦合非接触电导(C⁴D)与共聚焦激光诱导荧光(LIF)两种检测方法在毛细管柱上同一位置同时检测。3D打印的检测池采用了导电的复合聚乳酸(PLA)材料制作C⁴D的屏蔽层,采用普通的绝缘PLA材料支撑C⁴D金属管电极并隔离屏蔽层。两根金属管电极通过“打印-暂停-打印”的方式嵌入到检测池中,两电极被2 mm厚的导电屏蔽层隔开,在屏蔽层中有一直径为1 mm的圆形通孔用于LIF检测。该检测池与带流通式进样接口的自组装CE系统联用,用于同时检测无机离子和异硫氰酸荧光素(FITC)标记的氨基酸。研究优化了C⁴D激励信号频率与电泳缓冲液浓度,选用的电泳缓冲溶液为10 mmol/L 3-吗啉丙烷-1-磺酸(MOPS)与10 mmol/L二(2-羟乙基)亚氨基三(羟甲基)甲烷(Bis-Tris)的混合溶液,选用C⁴D激励频率为77 kHz。二合一检测池应用于内径为25 μm的毛细管时,C ⁴D对Na⁺、K⁺和Li⁺的检出限分别为2.2、2.0和2.6 μmol/L; LIF对荧光素和FITC的检出限分别为7.6和1.7 nmol/L。两种检测方法的相对标准偏差在0.3%至4.5%之间(n=3),工作曲线的相关系数r ²≥0.9904。采用3D打印技术可以在实验室内实现复杂结构的制作,降低了制作的成本,且便于方法的推广和改进。     

Nanoband electrode for high-performance in-channel amperometric detection in dual-channel microchip capillary electrophoresis

A nanoband electrode detector integrated with a dual-channel polydimethylsiloxane microchip is proposed for in-channel amperometric detection in microchip capillary electrophoresis. Gold nanoband electrodes, which were fabricated on SU-8 substrates with a 100-nm-width gold layer, were introduced into the dual-channel microchip to be an electrochemical detector. Due to the nano-sized width of the detector, the noise of the amperometric detection was significantly reduced, and a high separation resolution was achieved for monitoring the analytes. The detection sensitivity of the system was improved by high signal-to-noise ratio, and a low detection limit on microchip was obtained for p-aminophenol (2.09 nM). Because of the high resolution in measuring half-peak width, the plate number that is used to evaluate the separation efficiency was 1.5-fold higher than that using 50-μm-width electrochemical detector. The effect of sample injection time and data acquisition time on separation efficiency was investigated, and an attractive separation efficiency was achieved with a plate number up to 17,500.     

The Effects of the Electrode System Geometry on the Properties of Contactless Conductivity Detectors for Capillary Electrophoresis

The basic analytical parameters of contactless conductivity detectors with planar, semi‐tubular and tubular electrodes have been compared. It has been found that the differences in the analytical parameters of the detectors are not significant for analytical use. The mean values of baseline peak‐to‐peak noise of 0.27, 0.35 and 0.33 mV, sensitivities of 0.97, 2.08 and 2.27 mV/pg (for K⁺ ion), limits of detection of 0.93, 0.65 and 0.53, and the heights equivalent to a theoretical plate of 2.83, 2.39 and 2.40 μm were obtained for the detectors with planar, semi/tubular and tubular electrodes, respectively. Modifications of the basic detectors, namely a detector with thinned capillary wall and planar electrodes, and a detector with semi‐tubular electrodes placed one against the other on the opposite sides of the capillary were also tested. The configuration with the electrodes placed one against the other permits detector construction with zero gap between the electrodes without increasing the noise; when the electrodes overlap, the detector begins to operate as a permittivity detector.     

Applications of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE‐C4D) in pharmaceutical and biological analysis

Conductivity detection, which is universal in capillary electrophoresis (CE), has received considerable attention, since the introduction of the axial capacitively coupled contactless detector C⁴D in 1998. This detector is made of two electrodes which are placed cylindrically around the CE capillary and connected to the AC oscillator. The distance between the electrodes is the detection gap. In this review, applications of CE and MCE with C⁴D in pharmaceutical and biological analysis are presented.     

Sheath-flow electrochemical detection of amino acids with a copper wire electrode in capillary electrophoresis

Here, we report the detection of native amino acids using a sheath-flow electrochemical detector with a working electrode made of copper wire. A separation capillary that was inserted into a platinum tube in the detector acted as a grounded electrode for electrophoresis and as a flow channel for sheath liquid. Sheath liquid flowed outside the capillary to support the transport of the separated analytes to the working electrode for electrochemical detection. The copper wire electrode was aligned at the outlet of the capillary in a wall-jet configuration. Amino acids injected into the capillary were separated following elution from the end of the capillary and detection by the copper electrode. Three kinds of copper electrodes with different diameters-50, 125, and 300 μm-were examined to investigate the effect of the electrode diameter on sensitivity. The peak widths of the analytes were independent of the diameter of the working electrode, while the 300-μm electrode led to a decrease in the signal-to-noise ratio compared with the 50- and 125-μm electrodes, which showed no significant difference. The flow rate of the sheath liquid was also varied to optimize the detection conditions. The limits of detection for amino acids ranged from 4.4 to 27 μM under optimal conditions.     

一种基于双工作电极-双通道的毛细管电泳电化学检测系统

报道了一种双工作电极-双通道毛细管电泳电化学检测系统，实现电导和安培 同时检测或者安培与安培检测联用，使两种方法相互补充，发挥各自的优势。其中 ，工作电极与检测池的制作工艺简单，操作简便，通过不锈钢针管和毛细管作为套 管，无需三维微调装置即可简单实现双工作电极的准确放置及分离毛细管与工作电 极的准确对接，并根据分析体系的需要采用不同类型的工作电极和检测器；同时采 用复式滤波电路解决了不同检测器之间的电场叠加对输出信号的干扰问题。采用该 装置可以同时检测复杂体系中的电活性和惰性物质，或同时测定只能氧化或只能还 原的物质，还可以对具有氧化还原性质的物质进行纯度的确证。将该装置应用于实 际样品的测定，节约了分析时间，提高了分析速度，扩大了检测范围，结果令人满 意。     

Six orders of magnitude dynamic range in capillary electrophoresis with ultrasensitive laser-induced fluorescence detection

An ultrasensitive laser-induced fluorescence detector was used with capillary electrophoresis for the study of 5-carboxy-tetramethylrhodamine. The raw signal from the detector provided roughly three orders of magnitude dynamic range. The signal saturated at high analyte concentrations due to the dead time associated with the single-photon counting avalanche photodiode employed in the detector. The signal can be corrected for the detector dead time, providing an additional order of magnitude dynamic range. To further increase dynamic range, two fiber-optic beam-splitters were cascaded to generate a primary signal and two attenuated signals, each monitored by a single-photon counting avalanche photodiode. The combined signals from the three photodiodes are reasonably linear from the concentration detection limit of 3 pM to 10 μM, the maximum concentration investigated, a range of 3,000,000. Mass detection limits were 150 yoctomoles injected onto the capillary.     

A simplified poly(dimethylsiloxane) capillary electrophoresis microchip integrated with a low-noise contactless conductivity detector

A contactless conductivity detector integrated into a poly(dimethylsiloxane) microchip for electrophoresis is presented. It adopted the simplest configuration of electrodes commonly used in this detection mode for capillary electrophoresis microchips. Although the chip is based on a simple and effective design, it is able to obtain low detection levels due to the low noise of the detection circuit. A circuit based on a lock-in amplifier was designed on printed circuit boards to read out the signal. The property of the detection cell was studied by applying excitation signals of different frequencies and different amplitudes. It was found that the best detection limit could be achieved with a frequency of 50?kHz and amplitude of 20?V. The performance of the detector was demonstrated by successfully separating and detecting several inorganic ions and also a mixture of heavy metal ions. An average detection limit of 0.4?μM was obtained for inorganic cations. This value is significantly improved compared to similar microchip-based detectors. The presented detector could be promising for mass production due to its properties, such as simple construction, high degree of integration, high performance and low cost.