【作者】 姜小红；

【导师】 姜玮； 占金华；

【作者基本信息】 山东大学 ， 分析化学， 2014， 博士

【摘要】 有机污染物广泛分布于自然界中,给人类健康和社会环境带来危害,因此发展快速、经济、高灵敏的检测有机污染物的方法刻不容缓。传统检测有机污染物的方法主要有荧光光谱法、磷光光谱法、电化学方法、色谱法以及毛细管电泳方法等。这些方法一般都需要复杂昂贵的仪器,测试前需要对样品进行预处理,存在步骤复杂、测试周期长等缺点。表面增强拉曼光谱是目前常用的一种简单快速的分析方法,目前已经广泛应用于环境有机污染物的检测中。表面增强拉曼光谱具有高灵敏度、高选择性、受水和荧光信号干扰小的优点。利用表面增强拉曼光谱对分析物进行检测首先需要制备具有高的增强效果的基底,只有当分析物分子吸附到基底表面时,才能产生高的表面增强拉曼光谱信号。有机污染物难以吸附到贵金属基底的表面,使得直接通过表面增强拉曼光谱检测这些污染物存在一定的困难。可以对基底表面进行改性,修饰上和有机污染物具有相互作用的物质,利用表面修饰剂和有机污染物之间的作用将污染物吸附到基底表面,从而可以实现对污染物的表面增强拉曼光谱检测。本论文在铜箔上合成了银纳米颗粒聚集体,对基底表面进行修饰,实现了对多种环境污染物的检测。论文主要内容归纳如下：1.我们发展了一种利用铜箔上的银纳米颗粒聚集体通过表面增强拉曼光谱定性和定量检测多环芳烃的分析法。构建具有高的增强效果的拉曼基底对表面增强拉曼光谱检测非常重要。传统的基底容易受到激光热效应的影响,会得到重复性较差的拉曼信号。有文献报道铜箔上合成的银纳米结构在激光照射下具有高的稳定性。我们利用氯化亚锡作为“敏化剂”,利用硝酸银和铜箔之间的置换反应,通过循环浸泡的方式在铜箔上沉积了银纳米结构。我们采用X射线粉末衍射(XRD)和扫描电子显微镜(SEM)对合成的银纳米结构进行了表征。表明铜箔上合成的银结构为银纳米颗粒聚集体。为了得到具有高增强因子的基底材料,我们考查了循环次数和氯化亚锡的影响,表明在氯化亚锡存在条件下循环浸泡四次具有较高的增强。我们以银纳米颗粒聚集体作为基底,正己硫醇作为表面修饰剂,对多环芳烃进行检测,说明利用正己硫醇修饰的银纳米颗粒聚集体可以实现多环芳烃的表面增强拉曼光谱检测。研究表明,正己硫醇修饰的银纳米颗粒聚集体基底具有较好的稳定性、均一性和重复利用性。我们进一步利用正己硫醇修饰的基底对多环芳烃进行了定量检测,表面增强拉曼光谱信号和多环芳烃浓度的log-log关系图呈线性。2.我们利用便携式拉曼光谱仪通过表面增强拉曼光谱实现了对多溴联苯醚的检测。多溴联苯醚是一种常见的溴代阻燃剂,通常通过色谱方法进行检测,存在热降解和分辨率不足的缺点,另外,在进行色谱检测之前,需要进行复杂和费时的样品预富集过程。我们通过表面增强拉曼光谱技术对这类物质进行定性和定量检测。选择硫醇修饰的银纳米颗粒聚集体作为基底材料,基底表面的硫醇可以将多溴联苯醚预浓缩到基底表面。考查了不同链长硫醇(C6、C12和C18)修饰的基底对多溴联苯醚的检测效果,表明正己硫醇修饰的基底检测效果最佳。同时正己硫醇修饰的基底具有较高的稳定性和重复利用性。利用正己硫醇修饰的基底实现了实际海水中多溴联苯醚的检测,检测限为0.12mg·L-1以上研究表明表面增强拉曼光谱是检测多溴联苯醚的一种有效方法。3.我们选择巯基乙胺盐酸盐作为银纳米颗粒聚集体的表面修饰剂,实现了表面增强拉曼光谱对五氯酚的检测。五氯酚是一种常见的环境污染物,广泛作为杀虫剂、除草剂以及防腐剂等。目前五氯酚在空气、水、土壤甚至人的尿液、血液和组织液中都可以检测到。多项研究表明五氯酚能够造成生物急性中毒、干扰内分泌甚至致癌。对环境中五氯酚的监测至关重要,常用的检测五氯酚的方法是色谱法,这些方法一般都需要复杂的样品预处理过程。表面增强拉曼光谱是一种快速高灵敏的检测方法,目前在环境监测以及生物医学等方面具有广泛的应用。然而该分析方法的广泛应用仍然具有一定的限制,具有巯基、羧基和胺基等容易吸附到金属基底表面上的物质具有高的表面增强拉曼光谱信号,通常生物分子具有这些官能团,很容易吸附到基底表面具有高的信号可以实现高灵敏度的检测。然而环境中很多有机污染物,比如氯代杀虫剂、多环芳烃以及其它芳香化合物难以吸附到金银基底表面,通过表面增强拉曼光谱对这些物质的直接检测有一定的困难。对纳米颗粒表面进行修饰利用修饰剂和污染物之间的作用力可以将污染物分子富集到基底表面。常见的表面修饰剂和分析物之间的作用包括疏水作用、主客体作用、抗原抗体之间的特异性结合以及离子对作用。同时基底表面的修饰剂可以作为定量检测的内标。我们选择巯基乙胺盐酸盐作为表面修饰剂,巯基乙胺盐酸盐含有正电荷的-NH3+基团,该基团能够与PCP作用,巯基乙胺盐酸盐在表面增强拉曼光谱检测中起着双重作用：其一,通过静电作用将PCP预浓缩到基底表面,其二是在定量检测中作为内标物。巯基乙胺盐酸盐修饰的基底具有较好的均一性、稳定性和重复利用性。利用巯基乙胺盐酸盐修饰的基底实现了对PCP的定性和定量检测。更多还原

【Abstract】 Organic pollutants are widely distributed in the nature, which have severe adverse effects on human health and environment. It is crucial to develop rapid, economical and sensitive method for the detection of organic pollutants. The traditional analytical techniques for the detection of organic pollutants include fluorescence spectroscopy, phosphorescence spectroscopy, electrochemical methods, chromatographic method, capillary electrophoresis methods and so on. These methods generally require expensive equipment or complicated sample preparation before detection. Alternatively, surface-enhanced Raman spectroscopy (SERS) is a simple and rapid analytical method, which has been widely used in the detection of environmental organic pollutants. SERS has the advantages of high sensitivity, good selectivity and weak interference from water and fluorescent signals. High enhancement substrate and the analytes close to the substrate are important to SERS detection. However, the organic pollutants show weak affinity to the substrate surface, which make the SERS detection difficult. Modification of the substrate with some substances, which could adsorb the organic pollutants close to the substrate, may make the SERS detection of the organic pollutants possible.In this paper, silver nanoparticles aggregates were synthesized and modified with self-assembled monolayers and used as the SERS substrate to detect organic pollutants. The main contents can be summarized as follows:1. A simple, cost-effective and rapid method has been developed for qualitative and quantitative SERS detection of polycyclic aromatic hydrocarbons (PAHs) using silver nanoparticle aggregates on copper foil as the substrate. Fabrication of high enhancement substrate is crucial for SERS detection. However, the traditional substrate could be influenced by laser heating effect and irreversible signals were obtained. It has been reported that the silver nanostructures show high stability under the laser irradiation. In this work, SnCl2was used as the "sensitizer" and the silver nanostructures were generated based on the galvanic displacement reaction. The prepared substrate was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The SEM image confirmed that the copper foil surface is covered with dense silver nanoparticle aggregates. To obtain high-enhancement substrate, the influences of the number of circulation and SnCl2were investigated. The results indicated that the large enhancement substrate could be obtained under four cycles in the presence of SnCl2. The silver nanoparticle aggregates and alkanethiol were used as the substrate and the modifier to detect PAHs. Studies showed that the alkanethiol-modified silver nanoparticle aggregates could realize the SERS detection of PAHs. The substrate has good stability, uniformity and reproducibility. We further used the substrate to quantitative SERS detection of PAHs and the log-log plot of the normalized SERS intensity versus PAHs concentrations yielded a good linear relationship2. The SERS detection of polybrominated diphenylethers (PBDEs) was realized using a portable Raman spectrometer. PBDEs, one of the most common brominated flame retardants, are toxic and persistent, generally detected by the chromatographic method. In this work, qualitative and quantitative detection of PBDEs were explored based on surface-enhanced Raman spectroscopy (SERS) technique using a portable Raman spectrometer. Alkanethiol modified silver nanoparticle aggregates were used as the substrate and PBDEs could be pre-concentrated close to the substrate surface through their hydrophobic interactions with alkanethiol. The effect of alkanethiols with different chain length (C6、C12and C18) on the SERS detection of PBDEs was evaluated. It was shown that1-hexanethiol (HT) modified substrate has higher sensitivity, good stability and reusability. Qualitative and quantitative SERS detection of PBDEs in real sea water was accomplished, with the measured detection limits at1.2×102μg·L-1. These results illustrate SERS could be used as an effective method for the detection of PBDEs.3. Cysteamine-modified silver nanoparticle aggregates have been fabricated for pentachlorophenol (PCP) sensing by SERS using a portable Raman spectrometer. PCP is a common environmental contaminant, which has been widely used as insecticide, herbicide and wood preservative. PCP now can be detected in the air, water, soil, as well as in human urine, blood and adipose tissues. It is important to detect PCP. The traditional analytical techniques are chromatographic methods, which often need complex and time-consuming sample pretreatment. SERS is a rapid and sensitive analytical method, which has been widely used in biology, medicine, or environmental monitoring related fields. However, there are still some limitations that restrict the technique as SERS is observed when the analytes are close to the rough noble metal surfaces. Only these analytes with specific functional groups, such as thiol, carboxylic acid, and amine, etc., could easily adsorb onto the substrate surface and provide good signals to meet the ultrasensitive analysis. Biological related samples often contain these functional groups and hence have good singnals. However, a large group of organic pollutants in the environment characterized by nonfunctionalized groups, such as chlorinated pesticides, polycyclic aromatic hydrocarbons, trinitrotoluene, and other aromatic compounds, show weak affinity to gold or silver. It is difficult to direct detect these compounds by SERS, and thus many indirect methods emerged. Many methods rely on functionalized nanoparticles with different media to concentrate analytes close to the substrate surface. These strategies include hydrophobic interactions using alkanethiols, host-guest interactions using cyclodextrin, specific interactions using antibodies and aptamers, as well as electrostatic attraction of ion pairing. The surface modifier of the substrate may form a self-assembled monolayer (SAM) on the metal substrate, which could also be used as internal standards for the reliable quantitative assay. Cysteamine hydrochloride (Cys) was selected as the modifier, which bears positively charged groups-NH3+and could interact with the acidic PCP. Cys plays a dual role in the process: pre-concentration of PCP close to the substrate surface through their electrostatic interaction and acting as the internal spectral reference in the quantitative detection. Cys-modified substrate has good uniformity, stability and reusability. Qualitative and quantitative SERS detection of PCP were realized based on this substrate. This work is the first example to use Cys-functionalized substrate for SERS analysis of PCP.更多还原