【作者】 吴婷；

【导师】 叶建农； Jacques Delaire；

【作者基本信息】 华东师范大学 ， 分析化学， 2010， 博士

【摘要】 本论文主要介绍了三种微分析系统的开发及对环境污染物的检测研究,包括地表水中重金属离子的检测和生活污水处理厂水体中环境雌激素的检测。首先,我们研究了一种对铅离子进行选择性检测的流动注射微流控分析体系。其检测原理是基于一种荧光分子传感器（Calix-DANS4）对铅离子的高灵敏度和高选择性的响应。该荧光离子团是一种带有四个DANS1基团的杯芳烃。该铅离子检测微流控芯片由含有被动混合器的Y-型微通道和玻璃粘合而成。检测腔体的引入极大的提高了检测的灵敏度,检测时由光纤传导的两个365 nm紫外发光二极管对腔体中荧光分子同时激发,然后另一光纤组在和激发光垂直的角度进行荧光采集,并与光电倍增管耦合放大进行检测。在pH 3.2,乙腈/水=60/40,荧光分子浓度为1×10^-6摩尔/升时,该体系对铅离子的检测限可以达到2.5×10^-8摩尔/升,这已经低于世界卫生组织目前饮用水中铅离子含量指导标准中的最大值以及2013年的饮用水的欧洲标准。为了改善我们的流动注射微流控分析体系的灵敏度和选择性,以及消除其共存离子钙离子的干扰,我们在微流控分析前加入了固相萃取富集前处理过程。萃取柱是自制的填充了功能化3-氨基丙烷硅胶的Teflon微柱。在进行微柱固相萃取时,功能化硅胶在碱性条件下（pH=10）选择性吸附痕量铅离子,从而能与其他的干扰离子分离,特别是水中大量存在的钙离子和钠离子。在酸性条件下,铅离子能被可逆地从微柱上洗脱下来,富集倍数可达100倍。固相萃取前处理过程和荧光法微流控装置相结合,已被成功地用于自来水中铅离子的检测。该检测结果已用常规用于检测痕量铅离子的原子吸收光谱法进行了证明。在进行微流控体系分析检测时,我们发现体系外混合体系内检测和体系内由被动混合器混合再检测得到的滴定曲线存在很大的差异,初步表明该反应在我们的微流控体系中存在某些不完整性。利用一个快速反应模型在微流控体系中体系外混合和体系内混合的对比研究,我们证明了反应物在我们微流控分析体系中已经完全混合。为了更好地理解所研究荧光离子团和铅离子之间的络合作用,我们通过将微流控分析手段,停流方法（stopped-flow）和计算机模拟相结合的方法从理论和实验的角度同时研究该络合反应的机理和反应动力学,并分析和验证了已有实验结果的合理性。首先,我们进一步改善了我们的微流控分析体系的操作参数,如降低流速以增加传输时间,从而延长反应时间,这明显地缩小了和体系外混合得到的滴定曲线的差距。另外,通过改变微流控体系的几何构型,如延长的微通道,同样为了延长反应时间,两曲线已经接近重合,实验证明了该反应是个慢反应,在我们的微流控通道内,该络合反应尚未结束。然后,通过驰豫时间的分析方法,我们得到对于1:1络合反应,当荧光分子浓度远大于金属离子浓度时,铅离子浓度和驰豫时间的倒数成线性关系。我们用停流方法研究了在该反应条件下的反应速率,实验数据也证明在铅离子浓度大于等于十倍荧光分子浓度时,该线性关系成立,并由此得到络合反应的结合常数（k₁）。我们通过用软件SPECFIT对荧光光谱的分析和拟合得到了该反应的平衡常数,从来计算得到其解离常数(k_-1)。最后,我们用另一软件Chemical kineticssimulator对该反应进行计算机模拟,得到了对应于我们的微流控体系条件的理论曲线,和我们的实验曲线基本相符。本论文中所研究的另一金属离子检测器是基于微腔激光的光流体传感器。该传感器的原理主要是微腔激光材料对金属离子的选择性吸附导致其折射率的改变,从来引起微腔激光光谱的移动。本论文的工作主要是对该微腔激光材料的研究。我们主要研究了嵌段共聚物,因为其微相分离的特殊性,疏水段可以容纳激光染料,而亲水段在水中溶胀后可以容纳金属离子,从而具有发激光和离子传感的双重性能。我们主要研究了两种嵌段共聚物（PS-b-P2VP,PS-b-P4VP）,PS能容纳染料分子（DCM）,P2VP和P4VP与金属离子间可能有相互作用。借助于原子力显微镜（AFM）,我们研究了两种聚合物薄膜的表面形态,以及经过水处理和金属离子处理后的形态变化。借助于椭偏仪（ellipsometry）,我们研究了两种聚合物薄膜的折射率,以及经过水处理和金属离子处理后的折射率变化。表面形态和折射率变化表明,PS-b-P4VP对锌离子有特殊的响应。该聚合物进一步用于制作微腔激光以及光流体,并在光流体中测试该微腔激光通过水和锌离子溶液后的光谱移动。初期的实验结果表明,锌离子能引起光谱移动,但真正的原因还需进一步证明和探索。本论文中研究的最后一种微分析方法是关于微型毛细管电泳安培检测对污水厂中环境雌激素的检测研究。该小型化的毛细管电泳安培检测与固相萃取前处理相结合的方法首次成功地对五种环境雌激素:2,4-dichlorophenol（DCP）,4-tert-butylphenol（BP）,bisphenol A（BPA）,17α-ethynylestradiol（EE2）和4-n-nonylphenol（NP）进行了分离和检测。毛细管电泳的分离模式采用的是胶束电动色谱（MEKC）,有效地改善了分离效果。为了改善灵敏度,在分析前采用了固相萃取将被分析物进行富集。我们对分离检测的条件（如缓冲液的pH值和浓度,胶束的浓度,分离电压,进样时间）进行了优化,在最优条件下,该五种分析物在12分钟内有效地得到分离和检测。该方法成功地用于污水厂中的该五种环境雌激素的检测。更多还原

【Abstract】 This study describes the development and application of three microanalysis systems. The application domain is concentrated on environmental contaminations, mainly heavy metal ions in surface water and endocrine disrupting chemicals in sewage.A microfabricated device has been developed for the selective detection of lead in water. It is based on the use of a selective and sensitive fluorescent molecular sensor （Calix-DANS4） for lead which contains a calix[4]arene bearing four dansyl groups. The principle of this sensor is photoinduced charge transfer （PCT） which can cause a slight blue shift of both the absorption and fluorescence spectra in acidic condition after binding with lead ion. The microchip-based lead sensor is a Y-shape microchannel structured with a passive mixer and stuck on a glass substrate. The detection is performed by using a configuration in which the sensing molecules are excited by two optical fibres, each connected to a 365 nm UV LED, and the emitted light is collected by another optical fibre coupled with a photomulti-plier.A detection limit of 2.5×10^-8 mol L^-1 (i.e. 5.2μg L^-1) could be reached, which is lower than the maximum level of lead allowed in drinking water after 2013, according to European regulation.In order to improve the sensitivity of the previous microfluidic device and to get rid of interfering calcium ion, we developped a solid phase extraction preconcentration （SPE） stage with a micro-column filled with silica beads functionalized with aminopropyl groups （APS）. During SPE, the APS groups selectively adsorb the lead ions at basic pH （pH = 10） which allows its separation from others (Ca²⁺, Na⁺). In acidic medium （pH = 2）, lead is reversibly released and can be recovered in a 100 times more concentrated. The combination of SPE and previous fluorimetric microfluidic device was carried out for lead solutions of known concentrations in tap water. The results were proved by Atomic Absorption Spectroscopy.The study of the mechanism of the complexation between fluorescence molecular sensor （Calix-DANS4） and lead ion allows us to optimize the chip where the complexation occurs. The large difference between the calibration curves obtained for reactants mixed inside the chip and for injection of a premixed solution shows that the complexation is not finished at the end of the microchannel. A new microchip with a longer channel has permitted to approach the equilibrium state. Conventional stopped-flow method was also applied here to determine the real reaction kinetics and rate constants. The results show that this complexation at pH 3.2 is a relatively slow reaction, which takes several minutes for weak Pb²⁺ concentrations. It proves that the complexation in our microfluidic chips has not yet finished, as the transit times in all these microfluidic chips are less than 40 s.Another microanalysis system for metal ion sensing is an optofluidic sensor which combines optical elements （such as waveguide, laser...） and microfluidics for biological and chemical assays. A preliminary study of polymer microcavity laser for metal ions sensor in microfluidic channel is introduced in this thesis. The search of the microcavity laser materials is focused on diblock copolymers, especially two diblock copolymers （PS-b-P2VP, PS-b-P4VP）, which can form microphase separation to load laser dye （e.g. DCM） in the hydrophobic phase and metal ion in the hydrophilic phase. The morphologies and refractive index of their cast films are studied before fabricating the microcavity laser. Their responses to different environments （e.g. water, metal ion solutions...） are characterized by AFM and ellipsometry. The results show that PS-b-P4VP can exhibit remarkable changes both of morphology and refractive index when contacting with zinc ion solution, while zinc ion has no effect on PS-b-P2VP. The first optofluidic sensor is fabricated with a microcavity laser which is made of PS-b-P4VP doped with a laser dye （DCM） and placed in a PDMS microfluidic channel. Its laser spectral shifts in presence of pure water and zinc ion are both observed.Endocrine Disrupting Chemicals （EDCs） are anthropogenic substances that can interfere with the endocrine systems of living organisms. Their harmful effects on human health, when they reach a certain amount, have been discovered and are still being studied precisely. An integrated analytical method to monitor five environmental endocrine disrupting chemicals （EDCs）: 2,4-dichlorophenol （DCP）, 4-tert-butylphenol （BP）, bisphenol A （BPA）, 17α-ethynylestradiol （EE2） and 4-n-nonylphenol （NP）, is developed for the first time. This third microanalysis system is based on a solid-phase extraction and miniaturized micellar electrokinetic chromatography （MEKC） with amperometric detection （AD）. In order to get the optimum conditions of their separation and detection, several parameters including pH and concentration of running buffer, concentration of micelle, separation voltage and injection time are studied and optimized. The five EDCs are well separated under the optimum conditions within 12 min. This method is successfully applied for the determination of these five EDCs in sewage influent sample. Satisfactory extraction performances from sewage sample are obtained by solid-phase extraction （SPE）, using a HLB （waters） cartridge. Quantitative analysis shows that DCP, BP and BPA exist atμg L^-1 level in the selected sample, while EE2 and NP are not detected.更多还原