毛细管电泳电容耦合非接触电导检测器.pdf

仪表截木与传器
第12期
Instrument Technique and Sensor
No.12
毛细管电泳电容耦合非接触电导检测器
曾凡亚',苏建坡',赵书俊,张书胜2,张斌,卢艳艳
(1.郑州大学物理工程学院,河南郑州450001;2.郑州大学化学系,河南郑州450001)
摘要:设计了一种集激励、检测和数据采集功能于一体的毛细管电泳非接触电导检测器,采用文氏电挢振满器产生激
励信号,运用绝对值检波技术对检测信号进行处理,并设计USB数据采集电路和上位机软件,实现波形数据的采集、存情
和图谱的绘制。介绍了其检测原理、电路结构及实现,使用糖(0.04mol/L)+果糖(0.04molL)+蔗糖(0.04mol
L)样品进行了检测器重复性实验,并分离检测了6种酚酸,对检测器检測服作出评定。实验結果表明:峰保留时间和峰
面积相对标准差分别小于1%和7.5%,对酚酸的最低检测限为5ug/mL(信噪比S/N=3),检測器灵敏度高、重复性好。
关键词:毛细管电泳;非接触电导检测;文氏电桥振荡器;绝对値检波
中阳分类号:TH832文献标识码:A文章编号:1002-1841(2011)12-0003-03
Design of Capillary Electrophoresis Capacitively Coupled Contactless
Conductivity Detector
ZENG Fan-ya", SU Jian-po, ZHAO Shu-jun, ZHANG Shu-sheng", ZHANG Bin IU Yan-yan
1. College of Physics and Engineering, Zhengzhou University, A engzhou450001, China;
2 Department of Chemistry, Zhengzhou University, Zhen zhou 450001, China)
bstract: A kind of capillary electrophoresis capacitively coupled contactless conductivity detector(ce-cd)was designed
which had signal source, detection circuit and data acquisition unit. Wien bridge oscillator was used to get a signal source, and ab-
solute value demodulation was used to process signals And a data acquisition circuit with USB interface and software were designed
to acquire and store the signal data and draw spectrum. The principle and circuit of CE-C D were also introduced, glucose(0.04
mol/L)+fructose(0. 04 mol/L)+sucrose(.04 mol/L were took as samples to test the repeatability and at the same time, six
kinds of phenolic acids were separated and determined to evaluate the detection limit. The results show that the relative standard
deviation (RSD of peak retention time and area are less than 1% and 7. 5%o, and the detection limit of six kinds of phenolic acids
is 5 w/ml(signal noise ratio, S/N=3),the detector has good repeatability and high sensitivity
Key words: capillary electrophoresis; capacitively coupled contactless conductivity detection wien bridge oscillator; absolute value
demodulation
0引言
检测电路等进行了改进和发展°,但检测器的结构比较复
毛细管电泳( Capillary Electrophoresis,CE)是分析科学中继杂。文中设计了一种C"D检测器,灵敏度高,实现方法简单,成
高效液相色谱之后的又一重大进展,使分析科学从微升水平进本低廉。
人到纳升水平,在复杂药物分析、环境监测、生物工程和医学研1CEーCD检测原理
究等领域都取得了重大研究成果。非接触电导检测(Cor
检测池结构如图1所示,由两个管状电极相隔一定的距离
tactless Conductivity Detectior,CCD)技术作为毛细管电泳的一套在毛细管上,一个作为激励电极,一个作为接收电极,加在激
种检测方法,因其较高的灵敏度、良好的通用性、低廉的价格和励电极的交流信号通过毛细管壁耦合到溶液中,在接收电极获
校长的使用寿命,迅速成为分析科学的研究热点之一。早在得反映溶液组分浓度的信号。检测池简化的等效电路模型?
1980年,Cas就提出了四电极非接触电导检测,虽然解决了接如图2所示,由电极与溶液间的电容及溶液电阻组成。在未加
触电导检测中电极易污染和钝化的问题,但电极的制作与更换屏蔽电极的情况下,两检测电极间存在泄漏电容(图2(a)中
都极为不便];1998年, Zemann等和 Do Lago等分别同时C1),为改善检测池的频率响应特性,在两电极间加人接地屏蔽
提出轴向排列电极的电容耦合非接触电导检测,该技术大大简电极,此时泄漏电容可忽略。
化了电极的制作,提高了检测灵敏度,使非接触电导检测的应
由图2(b)的等效电路,检测池的阻抗为
用范围得到了极大的扩展。此后,国内外多个研究小组从检
Z=R+
原理、检测池等效电路模型等方面进行了研究,并对检测电极、
当激励信号频率f足够高时,电容的阻抗可忽略,结合
基金项目:国家自然科学基金(2107095),电分析化学国家重点实验室 Kohlraush公式,接收电极电流为
开放基金(2009002)
收稿日期:2011-03-28收修改稿日期:2011-06-30
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