【作者】 胡骢；

【导师】 胡斌；

【作者基本信息】 武汉大学 ， 分析化学， 2013， 博士

【摘要】 蓬勃发展的经济显著地提高了人们的物质生活水平,但是,也不可避免地带来一些新的问题,如环境污染、公共卫生及食品安全等。为了对环境污染及食品安全进行有效监控、治理和防范,环境和食品等样品中痕量污染物的分析显得十分必要,同时,它也给广大分析化学家们提出了巨大的挑战。实际样品中有机污染物的浓度往往较低且样品基质复杂,即使采用现代仪器分析方法,也难以进行直接分析。因此,分析工作者们通常采取在进行仪器分析之前,辅以合适的样品前处理技术以达到富集目标分析物,同时分离复杂基体的目的。搅拌棒吸附萃取技术(SBSE)是1999年由Baltussen等人提出的一种新型的、微型化样品前处理技术,具有富集倍数高、重现性好、不使用有机溶剂等优点,已被成功应用于环境、食品、生物样品中痕量有机物的分析。但是,目前SBSE的发展和应用同样受到一些限制,主要表现在：(1)商品化涂层种类少且价格昂贵,涂层为广谱性涂层,选择性差；(2)缺乏适用于极性物质分析,以及不同性质(如沸点、极性)物质同时分析的涂层、萃取模式和装置；(3)难以实现自动化。因此,发展萃取效率高、选择性好、使用寿命长、适用于极性物质分析,以及不同性质物质同时分析的涂层和萃取模式将会极大地促进SBSE的发展和应用。本论文的研究目的是：制备适用于极性有机物分析的、萃取效率高的新型极性涂层；制备复合材料涂层搅拌棒以实现不同极性有机物的同时分析；建立SBSE-色谱联用技术分析环境和食品等样品中有机污染物新方法。本论文的主要研究内容包括：(1)采用化学氧化聚合法合成了聚噻吩(PTH),首次成功地将富电子有机聚合物(PTH)应用于SBSE,该PTH可以通过共轭作用提高对有机磷农药的萃取效率。通过溶胶-凝胶(Sol-gel)法制备了聚二甲基硅氧烷/聚噻吩(PDMS/PTH)SBSE涂层,与电化学法聚合的PTH萃取涂层相比,本方法所制备的PDMS/PTH萃取涂层具有操作简单、涂覆量大、机械强度高等优点。在此基础上,建立了PDMS/PTH涂层SBSE与气相色谱-火焰光度检测器(GC-FPD)联用分析的新方法,并将其用于环境水样中五种有机磷农药(OPPs)(甲拌磷、对硫磷、马拉硫磷、杀螟硫磷和喹硫磷)的分析。在最佳操作条件下,对所建立方法的分析性能进行了评估,五种目标OPPs的检出限为0.011-0.038μg/L,富集倍数为56.7-80.9倍(理论富集倍数为100倍)。结果显示,PDMS/PTH涂层对OPPs萃取效率高,方法的定量下限低于美国环境保护署的规定,能够满足实际样品中OPPs的分析要求。(2)制备了一种氨基改性多壁碳纳米管(MWCNT-DDM),通过sol-gel法制备了一种新型MWCNT-DDM/PDMS涂层搅拌棒。建立了MWCNT-DDM/PDMS涂层搅拌林吸附萃取与高效液相色谱-紫外检测(?)(HPLC-UV)联用分析环境水和土壤样品中7种苯酚类化合物(苯酚、2-硝基苯酚、4-硝基苯酚、2,4-二甲基苯酚、4-氯-3-甲基苯酚、2-氯苯酚和2,4,6-三氯苯酚)的新方法。方法对氨基改性前后MWCNTS(?)目标分析物的萃取效率进行了比较,结果显示,氨基改性的MWCNTs通过疏水作用、π-π共轭作用和分子间氢键显著地提高了对极性苯酚类化合物的萃取效率。该方法制备的MWCNT-DDM/PDMS涂层搅拌林的制备重现性良好,其批内相对标准偏差(RSDs)为4.7-11.3%(n=9),批间RSDs为4.8-13.9%(n=8)。(3)通过sol-gel法制备了聚二甲基硅氧烷/β-环糊精/二乙烯基苯(PDMS/β-CD/DVB)涂层搅拌棒,据此,建立了PDMS/β-CD/DVB-SBSE-溶剂解吸(LD)-HPLC-UV检测肉类食品中四种雌激素(雌二醇、己烷雌酚、双烯雌酚和己烯雌酚)的新方法。PDMS涂层中添加的β-CD和DVB等成分可以通过共轭和“包络”等作用提高涂层对目标雌激素的萃取效率；采用正交设计实验对sol中PDMS、β-CD和DVB三组分的比例进行优化,获得了最优的溶胶组成。所制备的PDMS/β-CD/DVB涂层搅拌棒制备简单,重现性好,可重复使用50词以上,适用于肉类等基质复杂样品中目标雌激素的分析。(4)在室温条件下合成了三种金属骨架化合物(Metal-organic Frameworks, MOFs)(MOF-5、MOF-199和IRMOF-3),并通过sol-gel法制备了三种PDMS/MOIFs(PDMS/MOF-5、PDMS/MOF-199和PDMS/IRMOF-3)涂层搅拌林。对三种PDMS/MOFs涂层与自制/商品化PDMS涂层对于7种雌激素(雌二醇、双酚A、辛基酚、雌酮、乙炔雌二醇、双烯雌酚和己烯雌酚)的萃取效率进行了比较,结果显示PDMS/IRMOF-3具有最好的萃取效率,其可能的原因是IRMOF-3空穴大小以及氨基的存在提高了对目标雌激索的萃取效率。基于此,建立了PDMS/IRMOF-3-SBSE-LD-HPLC-UV检测环境水样中雌激素的新方法。结果表明,作：为一种性能优良的选择性萃取涂层,PDMS/MOFs在SBSE分析中具有巨大的应用能潜力。(5)采用水热法制备了一种MOFs萃取材料(Al-MIL-53-NH2),并通过sol-gel法制备了一种新型的PDMS/Al-MIL-53-NH2涂层搅拌棒。所制备的PDMS/Al-MIL-53-NH2涂层搅拌棒重现性良好,批间RSDs为3.9-8.1%(n=7),批内RSDs为5.9-14.9%(n=6),可重复使用40次以上。与通常用于PAHs分析的PDMS等SBSI涂层相比,PDMS/Al-MIL-53-NH2涂层具有萃取效率高和萃取动力学快的优势。基于此,建立了PDMS/Al-MIL-53SBSE与HPLC-FLD联用检测环境水样中PAHs的新方法。本方法具有检出限低、线性范围广、萃取效率高等优点,已被成功地应用于东湖水和长江水中PAHs的检测。(6)采用化学氧化法在室温条件下制备了聚苯胺(PANi),与羟基多壁碳纳米管(MWCNTs-OH)混合均匀后,通过粘附法制备了一种新型复合材料涂层搅拌棒。对复合材料PANi/MWCNTs-OH涂层中二者的比例进行了优化,建立了PANi/MWCNTs-OH复合涂层SBSE与HPLC-UV联用同时检测环境样品中极性、中等极性和非极性有机物(苯酚、非甾体药物和多氯联苯)的新方法,并成功地应用于环境水样和底泥样品中苯酚类等不同极性物质的同时检测。对不同极性物质的萃取主要基于疏水、共轭以及氢键作用。在最佳实验条件下,本方法对目标分析物的检测限为0.09-0.81μg/L,富集倍数为20.4-60.4倍,方法RSDs为6.5-11.8%(c=20μg/L)。该方法检出限低,对各种不同极性有机物均具有较好的萃取效率,为单根搅拌棒SBSE同时萃取不同极性目标分析物提供了一种新的途径。更多还原

【Abstract】 The rapid development of economy greatly improves human’s daily life, but it also brings about several problems, such as environmental pollution, public health and food safety. Thus, the analysis of contaminants at trace levels is of great significance for the monitoring of environmental and food security, which is also a great challenge for the analysts. Direct quantification of trace contaminants in real-world samples is often difficult even by the use of modern analytical instrumental methodology, due to the complex sample matrix and extremely low levels of target analytes. Therefore, suitable sample pretreatment techniques are often required prior to analysis for the enrichment of target analyte and separation of complex matrices. Stir bar sorptive extraction (SBSE) was developed in1999by Baltussen and co-workers. It possesses many merits such as high enrichment factor, good reproducibility, high adsorption capacity, high recoveries and solvent-free, and has been applied to the analysis of various analytes in environmental, food and biological samples. But there were several factors strictly limited the development of SBSE, including (1) commercial coating is very limited, expensive, with poor selectivity;(2) it is lack of novel coatings, extraction modes and devices which are suitable for the analysis of polar compounds or the simultaneous analysis of compounds with different properties,(3) it is difficult to be automated. Therefore, the preparation of novel coating with high extraction efficiency, selectivity, long lifetime, which is suitable for the analysis of polar compounds and simultaneous analysis of different compounds, is urgent and significant for the further development of SBSE and its application.The aim of this dissertation is to prepare new polar SBSE coatings for the preconcentration of polar compounds or simultaneous preconcentration of various compounds with different polarity, and to establish SBSE-gas chromatography/high performance liquid chromatography (GC/HPLC) methods for the analysis of organic contaminants in environmental and food samples. The major contents of this dissertation are described as follows:(1) Polythiophene (PTH) was synthesized by chemical oxidative polymerization method, and PDMS/PTH coated stir bar was prepared by sol-gel technique. This work introduced electron-rich organic polymer (PTH) to SBSE coating, which significantly benefit the extraction of target organophosphorus pesticides (OPPs) by conjugation. Compared with PTH fiber coating prepared by electrochemical polymerization method, the prepared PDMS/PTH coating by sol-gel method possesses many advantages such as simplicity, high coating capacity and mechanical strength. Based on it, a method of polydimethylsiloxane/(PDMS)/PTH coated SBSE coupled to liquid desorption (LD)-large volume injection(LVI)-gas chromatography-flame photometric detection (GC-FPD) was proposed for the determination of five interest OPPs (phorate, fenitrothion, malathion, parathion and quinalphos) in environmental water samples. Under the optimal conditions, the limits of detection (LODs, S/N=3) were found to be in the range of0.011-0.038μg/L for the five target OPPs, and the enrichment factors were varying from56.7to80.9-fold (theory enrichment factor was100-fold). The results showed that the PDMS/PTH coating has high extraction efficiency and fast extraction dynamics for target OPPs and the limits of quantification met the requirements of real sample analysis.(2) An amino modified multi-walled carbon nanotubes/polydimethylsiloxane (multi-walled carbon nanotubes-4,4’-diaminodiphenylmethane/polydimethylsiloxane, MWCNTs-DDM/PDMS) was synthesized, and utilized as a novel coating for SBSE of seven phenols(including phenol,2-chlorophenol,2-nitrophenol,4-nitrophenol,2,4-dimethylphenol, p-choro-m-cresol and2,4,6-trichlorphenol)in environmental water and soil samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. Compared with the MWCNTs-COOH/PDMS coated stir bar, the prepared MWCNTs-DDM/PDMS coated stir bar exhibited better extraction efficiency for the target phenols. And the preparation reproducibility of MWCNTs-DDM/PDMS coated stir bars was also investigated with the relative standard deviations (RSDs) ranging from4.7to11.3%(n=9) in one batch and from4.8to13.9%(n=8) among different batches, which shows that good reproducibility was obtained for the preparation of MWCNTs-DDM/PDMS coated stir bars. Under the optimal conditions, the proposed MWCNTs-DDM/PDMS-SBSL-LD-HPLC-UV provided LODs of0.14-1.76μg/L for target phenols, and was successfully applied for the analysis of target phenols in environmental water and soil samples.(3) Poly(dimethylsiloxane)/β-cyclodextrin/divinylbenzcne (PDMS/β-CD/DVB)-coated stir bar was prepared by sol-gel technique, and a method of PDMS/β-CD/DVB SBSE combined with HPLC-UV detection for the determination of four estrogens(17-β-Estradiol, dienestrol, diethylstilbestrol and hexestrol) was proposed. The influence of the coating composition on SBSE of target estrogens was investigated by an orthogonal experiment design, and the optimal PDMS/β-CD/DVB coated stir bar was obtained.The addition of β-CD and DVB in the coating increased the extraction efficiency of target estrogens through π-π conjugation and "inclusion" interaction. The prepared PDMS/β-CD/DVB coated stir bar has many advantages such as simplicity, good reproducibility, long lifetime (more than50 times) and suitable for the complex food sample analysis.(4) Three kinds of metal-organic frameworks (MOFs, MOF-5, MOF-199and IRMOF-3) were introduced in SBSE and novel PDMS/MOFs (including PDMS/MOF-5, PDMS/MOF-199and PDMS/IRMOF-3) coated stir bars were prepared by sol-gel technique. These PDMS/MOFs SBSE coatings were critically compared with self-prepared/commercial PDMS SBSE coating for the extraction of seven target estrogens (17-β-estradiol, dienestrol, diethylstilbestrol, estrone,4-t-octylphenol, bisphenol-A and17a-ethynylestradiol), and the results showed that PDMS/IRMOF-3exhibited highest extraction efficiency, probably due to the match of cavity size and the function of amino group. Based on the above facts, a novel method of PDMS/IRMOF-3coating SBSE-HPLC-UV detection was developed for the determination of seven target estrogens in environmental water samples. The high extraction efficiency and rapid extraction dynamics of the PDMS/IRMOF-3coating for the target estrogens demonstrates a great application potential of the PDMS/MOFs coating in SBSE with good selectivity.(5) A MOFs (Al-MIL-53-NH2) was synthesized by hydrothermal method, and a PDMS/Al-MIL-53-NH2coated stir bar was prepared with sol-gel technique. A new method of PDMS/Al-MIL-53-NH2SBSE combined with HPLC-fluorescence (FLD) for the determination of15polycyclic aromatic hydrocarbons (PAHs) in environmental water samples was proposed. The prepared PDMS/Al-MIL-53-NH2coated stir bar exhibited good preparation reproducibility and mechanical strength, and it can be reused for more than40times. The developed method is characterized with LODs, high extraction efficiency and wide linear range for the target PAHs, and shows a good application potential for the analysis of PAHs in various environmental samples.(6) Polyaniline (PANi), which was synthesized by chemical oxidative polymerization method, was mixed homogeneously with hydroxy-multi-walled carbon nanotubes (MWCNTs-OH) with grinding, and the mixture was employed for the preparation of a novel composite coating by adhesion method. The extraction performance of PANi/MWCNTs-OH composite coating for different kinds of analytes with different polarity was investigated, and a new method of PANi/MWCNTs-OH-SBSE-HPLC-UV was proposed for the simultaneous detection of polar, midium polar and apolar compounds(phenols, non-steroidal anti-inflammatory drugs, polychlorinated biphenyles) in environmental water and sediment samples. The developed method has many advantages, such as low LODs, high extraction efficiency for each analyte, and provides a new idea for simultaneous preconcentration and analysis of diffient polarity compounds by use of one single stir bar with one kind of coating in SBSE.更多还原