【作者】 张海涛；

【导师】 叶建农； Isabelle LERAY；

【作者基本信息】 华东师范大学 ， 分析化学， 2014， 博士

【摘要】 本论文研究的目的是检测环境污染物,主要是地表水中的重金属离子和饮用水中的消毒副产物。根据这两类物质的不同性质采用相应的两种方法：一类是基于荧光分子传感器的微流控分析法,另一类是电导检测法。在第一部分,两种荧光分子传感器和几种微流控芯片被用于地表水中重金属离子的检测。此外,对微流控芯片系统进行了改进。一种微流控芯片被设计和制作,用于水中镉离子的选择性检测。在该芯片中,使用了荧光分子探针Rhod-5N对镉离子进行响应。Rhod-5N是由BAPTA基团和一个罗丹明荧光基团组成的。其原理基于光诱导电子转移的发生,在按1：1络合的反应中,电子从BAPTA的一个芳香族氨基上转移到罗丹明荧光基团上。为了消除铅离子的干扰,使用了固相微萃取技术用于分离铅离子和镉离子。然后将探针和分离对象都引入微分析通道中,并使用525nm的UV LED激发。采集荧光信号,得到0-2μM范围内(Rhod-5N,1μgL-1)。的标准曲线,检测限为4nM (0.45μgL-1).使用飞秒激光刻蚀法制作一种新的PMMA微流控芯片,并在分子探针Rhod-5N的帮助下,测试其用于镉离子检测。结果与常用的比色皿和PDMS微流控芯片进行对比。遗憾的是,Rhod-5N吸附在PMMA聚合物分子上,从而影响了荧光检测的响应,检测限低于其在PDMS芯片中的结果。一种水溶性荧光分子探针DPPS-PEG被用于汞离子检测,该分子是DPPE的衍生物,其后嫁接一个PEG基团以提高水溶性。响应的原理是汞离子与膦硫键中的硫原子以1：1或者1：2的比例络合。在比色皿中得到的检测限是3.8nM。然后使用一种特别为汞离子检测设计制作的长检测通道的微流控芯片。反应物溶剂为有机-水溶液(CH3CN/H2O80:20, pH=4.0),并且添加2-3×10-4Triton×100用于得到稳定的荧光信号。检测限为10nM(2.0μgL-1)。在PDMS微流控系统中,常常产生气泡干扰荧光检测的现象,为了解决这个问题,本文采取了一些改进措施。三种措施被用于分离并排除气泡,包括气泡分离器的制作,PDMS亲水性表面处理和芯片中Phase-guide设计。气泡分离器的原理是利用浮力使气泡和液体在进入微流控分析系统之前分离并排除。PDMS的表面处理成亲水性的方法有两种,一种是使用O2plasma(简单,有效,但不稳定),另一种是PEG基团嫁接在PDMS表面(有效并且稳定)。缺点是PEG键合到PDMS表面以后对荧光分子可能发生吸附作用。Phase-guide在检测室中的设计和制作,可以控制灌流。气泡清空检测室,而反应物溶液沿着Phase-guide向前推进并充满了检测室。总之,这些改进对预防,分离和消除气泡非常有效。第二部分中采用了电膜萃取-毛细管区带电泳-电容耦合非接触式电导检测法(CE-C4D),建立了一种检测饮用水中的五种卤代乙酸(HAAs)的新方法。目标分析物卤代乙酸在电场推动下,萃取进入有机膜(使用有机溶剂正辛醇固定在中空纤维膜上),然后再反萃取到10微升的接收相中。富集后得到的溶液直接通过CE-C4D进行检测,无需衍生。本实验研究了缓冲溶液、分离电压、进样时间等条件对卤代乙酸的分离度、检测限、回收率的影响。在最佳条件下,饮用水中的五种卤代乙酸(一氯乙酸,二氯乙酸,三氯乙酸,一溴乙酸,二溴乙酸)可以在23min内可以实现基线分离,分析物的浓度和峰面积之间有良好的线性关系,相关系数r>0.999。本实验在30分钟的富集时间内,得到了430-671的富集倍数(EFs)。五种卤代乙酸峰的检测限为0.165ng/mL到0.609ng/mL,面积的相对标准偏差为1.17%-7.08%。本实验方法与传统的气相色谱分析法相比,不需要复杂的样品准备和衍生,为卤代乙酸的分析提供了一种可选择的新方法。更多还原

【Abstract】 This thesis is aimed at environmental contaminations detection, mainly heavy metal ions in surface water and disinfection by-products (DBPs) in drinking water. The two categories of contaminations have different properties so that two correspondent methods were developed:one is based on fluorescent molecular sensors in a microfabricated device, the other one is based on conductive detection.In the first part, two fluorescent molecular sensors and several microfluidic devices were developed and applied for heavy metal ions detection in surface water. Further more, some improvements of the performance of microfluidic chips were made.A microfabricated device has been designed and fabricated for selective detection of cadmium ions in water. This method is based on a fluorescent molecular sensor for cadmium sensing in microfluidic chip. Rhod-5N consists of BAPTA moiety and a rhodamine fluorophore. The principle of this probe is photoinduced electron transfer occurring from one of the aromatic amine groups of BAPTA moiety to the rhodamine fluorophore in1:1complex. To eliminate the interference of lead, a solid phase extraction (SPE) preconcentration process was used to separate cadmium and lead. Then the sensor and analyte solutions were introduced into the microchannel and excited by a525nm UV LED. The fluorescence signals were collected and the calibration curve ranges from0to2μM (Rhod-5N1μM), and the limit of detection is4nM (0.45μg L-1).A new microchip made of PMMA was fabricated by femtosecond laser ablation and tested for Cd2+sensing based on a fluorescent molecular sensor Rhod-5N. The results were compared with that in cuvette and in PDMS-based microchip. Unfortunately, Rhod-5N molecules adsorbed on PMMA polymers and the adsorption affects the response of fluorescence detection, and the limit of detection is much lower than in PDMS-glass chip.A water soluble fluorescent sensor (DPPS-PEG) was used for Hg2+sensing, which is a diphenylphosphanomethane (DPPE) derivative with phosphane sulfide, and a poly(ethylene oxide)(PEG) group introduced to increase the water solubility. The principle of this fluorescent sensor is Hg2+interacted with sulfur atom of phosphane sulfide in1:1or1:2complex. The detection limit obtained in cuvette is3.8nM. Then a long microchip based on PDMS and glass was fabricated for mercury ions detection. The reactants were prepared in organic-aquous solution (CH3CN/H2O80:20at pH4.0), and2～3×10-4Triton X100was added to obtain stable fluorescence signals. The detection limit is about10nM (2.0μg L-1).In PDMS-based microfluidic system, air bubbles always occur and affect the fluorescence detection, so some improvements were developed to solve this problem. Three strategies were studied for trapping and debubbling of air bubbles, including portable bubble trap fabrication, hydrophilic PDMS surface treatment and phase-guide in microchip design. The bubble trap is based on the principle of buoyant force so that liquid and air can be separated before introduced into the micro-channel. The hydrophilic treatments were realized by two ways, O2plasma treatment (simple and convenient, but unstable) or PEG-coating on PDMS surface (effective and stable). The drawback is that fluorescent molecules are adsorbed on PEG grafted PDMS surface. Phase-guide was designed and fabricated in the detection chamber, and enable the control of priming. Air bubbles emptied the chamber and the overflow filling the chamber along the phase-guide wall. In general, the work is helpful for air bubbles prevention, separation and elimination.A novel method for sensitive determination of five priority haloacetic acids (HAAs) in water systems has been developed based on electromembrane extraction (EME) prior to capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D). The target HAAs were extracted into the supported liquid membrane (using a polypropylene membrane supporting1-octanol), and then back-extracted into few microliters of an acceptor solution. The extracted solution was directly analyzed by CE-C4D without derivatization. Several factors that affect separation, detection and extraction efficiency were investigated. Under the optimum conditions, five HAAs (monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid) could be well separated from other components coexisting in water samples within23min, exhibiting a linear calibration over three orders of magnitude (r>0.999); the obtained enrichment factors (EFs) at430-671were obtained in a30min of extraction, and the limits of detection were in the range of0.165-0.609μg/L with relative standard deviation between1.17%and7.08%. This approach offers an attractive alternative to the official proposed method, which requires complex sample preparation and derivatization prior to analysis by gas chromatography.更多还原