【作者】 张帅华；

【导师】 王志； 王春；

【作者基本信息】 河北农业大学 ， 分析化学， 2010， 硕士

【摘要】 毛细管电泳(Capillary Electrophoresis, CE)以其分离效率高、分析时间短、样品需要量少、操作费用低等优点,日益成为一种高效的分离分析方法。但由于其进样体积小和检测光程短,对常用的紫外检测器而言,CE的一个主要缺陷是灵敏度较低,解决此问题的一个有效途径是采用离线或在线样品富集的方法。推扫是胶束毛细管电动色谱(Micellar electrokinetic chromatography, MEKC)操作模式下的一种在线富集技术,其基本原理是在MEKC中当假固定相穿越不含假固定相的样品区带时,由于两相分配作用或静电作用,分析物被萃取到胶束相,胶束相推扫富集分析物形成一个窄的样品区带。带电荷的或中性分析物均可被推扫富集,推扫富集技术具有广泛的应用前景。传统的样品前处理技术如液液萃取、固相萃取、沉淀和过滤等,存在操作繁琐耗时,需要使用大量的对人体和环境有毒或有害的有机溶剂等缺点。分散液相微萃取是2006年提出的一种新型样品前处理技术,一次萃取过程仅需十几微升有机溶剂,是一种对环境友好的样品前处理方法。该方法具有集采样、萃取和浓缩于一体,操作简单、快速、成本低且富集效率高等优点。本论文将分散液液微萃取(Dispersive liquid-liquid microextraction, DLLME)与胶束毛细管电动色谱在线推扫富集技术(On-line sweeping concentration technique in micellar electrokinetic chromatography, sweeping-MEKC)联用,并结合分散固相萃取(Dispersive solid-phase extraction,DSPE)净化技术,建立了水样、蔬果、土壤等环境样品中的三嗪类除草剂,氨基甲酸酯类农药,磺酰脲类除草剂等的高效、灵敏和选择性好的检测方法。在系统查阅有关文献资料的基础上,进行了以下研究工作:1.建立了胶束毛细管电动色谱在线推扫测定环境水样中的三嗪类除草剂残留的新方法。经过实验优化,最佳分离条件为:分离缓冲溶液(buffer)为pH= 2.5的50 mM H3PO4,100 mM SDS,20%甲醇(v/v)。在1.0 psi进样60 s,分离电压-20 kV,检测波长220 nm,25°C。与常规胶束毛细管电动色谱相比,富集倍率达到60~200倍。采用马钱子碱为内标,扑草净、西玛津和阿特拉津在0.005~5.0,0.05~5.0和0.05~5.0μg/mL范围内与内标物峰面积比呈良好线性关系,线性相关系数分别为0.998,0.997和0.997,其检出限分别为0.5 ng/mL,9.0 ng/mL和9.0 ng/mL(信噪比为3: 1),此方法用于环境水样中的三嗪类除草剂扑草净、西玛津、阿特拉津的测定,取得了满意的结果。2.建立了分散液液微萃取与胶束毛细管电动色谱在线推扫测定苹果中的氨基甲酸酯类农药(甲硫威、仲丁威、乙霉威、西维因、异丙威和速灭威)残留的快速、灵敏的新方法。并对影响萃取和推扫效果的因素,萃取剂和分散剂的种类及用量,萃取时间,盐浓度,样品基质和缓冲溶液浓度等进行了优化。在最优条件下,此方法的富集倍率达到469~1772倍(峰面积),检出限为2.0~3.0 ng/g,定量限(信噪比为10: 1)6.0~9.0 ng/g,线性范围是分析物的定量限到500 ng/g。日内和日间相对标准偏差范围分别是3.0% ~5.6%(n=5)和5.4%~8.3%(n=15)。在苹果中加标浓度为20 ng/g和100 ng/g的相对回收率85.4%~113.3%之间,相对标准偏差低于7.4%。该方法已成功地应用于分析目标苹果样品中的氨基甲酸酯残留。3.建立了分散液液微萃取与胶束毛细管电动色谱在线推扫测水样中的磺酰脲类除草剂残留的新方法。并对影响萃取和推扫效果的参数,例如萃取剂和分散剂的种类及用量,萃取时间和加盐量,缓冲溶液pH,缓冲溶液浓度等进行了优化。在最优条件下,五种除草剂(甲磺隆、氯磺隆、苄嘧磺隆、苯磺隆和氯嘧磺隆)的富集倍率高达3296~5086(峰面积)。线性范围在分析物的定量限(LOQs)~100.0μg/mL之间,检出限为0.2~0.5μg/mL。日内和日间相对标准偏差低于5.3%(n=5)和6.1%(n=15)。湖水、井水和自来水的加标回收率在5 ng/mL和20 ng/mL的两个浓度水平上为78.0%~108.0%之间,相对标准偏差低于7.2%。该方法已成功地应用于分析实际水样中的磺酰脲类除草剂残留。4.建立了分散固相萃取净化与分散液液微萃取联用萃取土壤样品中磺酰脲类除草剂,并利用胶束毛细管电动色谱在线推扫富集检测。苄嘧磺隆、苯磺隆和氯嘧磺隆在1.7~200 ng/g,甲磺隆、氯磺隆在3.3~200 ng/g范围内呈良好的线性关系。5类磺酰脲类除草剂的检出限在0.5~1.0 ng/g之间。土壤样品的3个不同浓度梯度(5.0,20.0和100.0 ng/g)的加标回收率在75.2%~93.5%之间,相对标准偏差RSDs低于7.6%。与其他土壤样品中的磺酰脲类除草剂前处理方法相比,DSPE-DLLME-Sweeping具有灵敏度高、分析时间短、环境友好和操作简便等优点,应用于测定实际土样中的分析取得了满意结果。更多还原

【Abstract】 Capillary electrophoresis (CE) has been recognized as a highly attractive separation technique due to its high separation efficiency, short analysis time, small sample requirements and low operation cost. However, the main drawback of CE is the poor concentration sensitivity due to the small injection volumes and a short optical path length in the most commonly used UV detection. One solution to the problem is to apply off-line and/ or on-line sample concentration methods. Sweeping, an on-line sample concentration technique, is defined as a phenomenon where analytes are picked up and concentrated by the pseudostationary phase that penetrates the sample zone containing no pseudostationary phase in micellar electrokinetic chromatography (MEKC). In sweeping, both charged and neutral analytes can be preconcentrated, making it a versatile enrichment technique. Conventional sample preparation methods, such as liquid-liquid extarction and solid phase exrtaction, are time- and solvent- consuming and often involve several complicated procedures. In 2006, Assadi and co-workers developed a novel liquid-phase microextraction technique, named dispersive liquid-liquid microextraction (DLLME). The method is based on the use of a ternary component solvent system. The advantages of DLLME method are environmental friendliness, simplicity of operation, rapidity, low-cost, and high-recovery and high enrichment factor.In this work, on the basis of dispersive liquid–liquid microextraction (DLLME) and dispersive solid-phase extraction (DSPE) technique in combination with on-line sweeping concentration technique in micellar electrokinetic chromatography (sweeping-MEKC), several analytical methods were developed for the determination of some pesticide residues in water, soil and agricultural samples. This thesis is mainly concerned with the following aspects:1. The application of an on-line sweeping concentration technique in micellar electrokinetic chromatography was investigated for the determination of atrazine, simazine and prometryn in water samples. Various parameters affecting sample enrichment and separation efficiency were systematically studied. Compared with the conventional MEKC method, up to 60~200 fold improvement in concentration sensivity was achieved in terms of peak height by using this sweeping injection technique. The compound strychnine was used as the internal standard for the improvement of the experimental reproducibility, a good linear relationship existed in the range of 0.005~5.0, 0.05~5.0 and 0.05~5.0μg/mL of each herbcides in water samples with the correlation coefficients (r) of 0.998, 0.997 and 0.997, and the detection limits (S/N= 3:1) for atrazine, simazine and prometryn were 9, 9 and 0.5 ng/mL, respectively. This method has been successfully applied to the analysis of atrazine, simazine and prometryn in lake, steam and ground water.2. A novel method was developed by using dispersive liquid–liquid microextraction (DLLME) coupled with sweeping-MEKC for the multiresidue analysis of six commonly used carbamate pesticides (methiocarb, fenobcarb, diethofencarb, carbaryl, isoprocarb and tsumacide) in apples. Parameters that affect the extraction and sweeping efficiency, such as the kind and volume of the extraction and disperser solvent, extraction time and salt addition, sample matrix and organic modifiers concentration in separation buffer were investigated and optimized. Under the optimum conditions, the enrichment factors were achieved in the range of 469~1772. The linearity of the method was obtained in the range of the limits of quantification (LOQs, S/N=10)-500 ng/g, with the correlation coefficients (r) ranging from 0.995 to 0.999. The limits of detection (LODs, S/N= 3: 1) were 2.0~3.0 ng/g and LOQs 6.0~9.0 ng/g. The intraday relative standard deviations (RSDs) varied from 3.0% to 5.6% (n=5) and interday from 5.4% to 8.3% (n =10). The recoveries of the six carbamates in apples at spiking levels of 20 ng/g and 100 ng/g were ranging from 85.4% to 113.3% with the RSDs lower than 7.4%. The proposed method has been successfully applied to the analysis of target carbamate residues in apple samples with satisfactory results.3. A rapid and sensitive method for the multiresidue analysis of sulfonylurea herbicides (chlorimuron ethyl, bensulfuron methyl, tribenuron methyl, chlorsulfuron, and metsulfuron methyl) in environment waters was developed using DLLME coupled with sweeping-MEKC. Parameters that affect the extraction and sweeping efficiency, such as the kind and volume of the extraction and disperser solvent, extraction time and salt addition, and the pH and concentration of the separation buffer were investigated and optimized. Under the optimum conditions, the enrichment factors were achieved in the range of 3296~5086 (Peak Area). The linearity of the method was obtained in the range of LOQs~100.0μg/mL with the correlation coefficients (r) ranging from 0.997 to 0.999. The limits of detection were 0.2~0.5 ng/mL. The intraday relative standard deviations (RSDs) varied from 1.2 % to 5.3 % (n=5) and interday from 2.6% to 6.1% (n =15). The recoveries of the five herbicides in water samples at spiking levels of 5.0 ng/mL and 20.0 ng/mL were ranging from 78.0% to 108.0% with the RSDs below 7.2%. The proposed method has been successfully applied to the analysis of target herbicide residues in water samples.4. A novel approach, dispersive solid-phase extraction followed by dispersive liquid-liquid microextraction (DLLME), was established for extraction of five commonly used sulfonylurea herbicides in soils prior to determination by sweeping-MEKC. Parameters that affect the extraction and sweeping efficiency were investigated and optimized. The linearity of the method for chlorimuron ethyl, bensulfuron methyl was in the range of 3.3~200 ng/g, and tribenuron methyl, chlorsulfuron, and metsulfuron methyl in the range of 1.7~200 ng/g, with the correlation coefficients (r) ranging from 0.997 to 0.998. The limits of detection (LODs) ranged from 0.2 to 0.5 ng/g. The intraday relative standard deviations (RSDs, n= 5) were below 5.3 % and interday RSDs (n= 15) within 6.8%. The recoveries of the method for the five sulfonylureas from soil samples at spiking levels of 5.0, 20.0 and 100.0 ng/g were 75.2%~93.5%, respectively. The proposed method has been successfully applied to the analysis of the target sulfonylurea herbicide residues in soil samples.更多还原