功能化石墨烯电化学传感器检测烟碱类农药的研究
发布时间:2018-01-01 03:28
本文关键词:功能化石墨烯电化学传感器检测烟碱类农药的研究 出处:《哈尔滨工业大学》2017年博士论文 论文类型:学位论文
更多相关文章: 石墨烯 烟碱类农药检测 电化学传感器 β-环糊精 表面分子印迹 壳寡糖-三维石墨烯
【摘要】:烟碱农药是世界上销售量最大的杀虫剂之一,但是长期滥用和违规使用导致农产品中低毒低残留农药严重超标,引起人们潜在健康问题以及“绿色贸易壁垒”。中国作为农业大国,亟需建立快速、灵敏、价格低廉的烟碱农药大规模现场检验监测技术。电化学传感器技术凭借响应快速、设备便携、成本低、操作简单等优点,逐渐成为农药残留现场侦测中最具有活力的手段之一。随着超分子识别技术、表面分子印迹技术及三维多孔材料的快速发展,将其与高电催化活性的石墨烯结合,应用于电化学传感器的核心元件——工作电极,以提高电化学检测方法的灵敏度、选择性和线性范围,是烟碱农残电化学检测的重要研究方向,也是分析工作者面临的巨大挑战。基于这样的研究目的,本文的主要研究内容如下:采用简单的湿法合成路线合成了β-环糊精-还原氧化石墨烯(β-CD-r GO),并将其修饰于玻碳电极表面,构建了β-环糊精-石墨烯电化学传感器。β-CD不仅作为还原氧化石墨烯(r GO)的稳定剂,同时也作为超分子主体识别客体分子哌虫啶(IPP),通过形成超分子包络物而将IPP带到石墨烯表面,从而增强电化学响应信号。与裸电极(GCE)和石墨烯修饰电极(r GO/GCE)相比,我国自主研发的新型烟碱农药哌虫啶(IPP)在β-CD-r GO/GCE上的不可逆还原峰电流值分别增加了14倍和2倍,显著提高了IPP检测灵敏度。为了进一步提高烟碱类农药的检测特异性,在石墨烯载体表面成功嫁接了分子印迹聚合物薄膜。构建的石墨烯表面分子印迹电化学传感器显著提高了烟碱农药电化学检测的电化学响应信号、识别特异性,缩短了响应平衡时间。试验创新性地采用对乙烯基苯甲酸(VBA,具有连接交联剂的烯基单元、结合模板分子的识别基团以及与石墨烯通过π-π相互作用而连接的苯环),在石墨烯(GN)表面成功负载单层均一的分子印迹(MIPs)膜,制备了石墨烯表面分子印迹聚合物(MIPs/GN)。分子印迹膜厚仅1.9nm,远低于文献中报道的石墨烯表面的分子印迹膜厚度17nm。GN/MIPs/GCE对吡虫啉的印迹因子达到2.3,显著高于同类烟碱农药,表明特异性良好。由于β-CD-r GO和MIPs/GN仅修饰于玻碳电极表面,识别位点有限,使得线性范围较窄,因此,本文采用水热法合成了壳寡糖-三维石墨烯,增加电极有效表面积,据此构建了壳寡糖-三维石墨烯电化学传感器。首先考察了影响三维石墨烯前驱体氧化石墨烯的超声剥离频率、超声剥离时间、氧化石墨烯片径。随后,利用壳寡糖带正电荷的特性,使其与带负电荷的氧化石墨烯结合,制备了孔洞均匀、结构稳定的壳寡糖修饰三维石墨烯。与未修饰的三维石墨烯相比较,壳寡糖-三维石墨烯电极在磷酸盐缓冲溶液(PBS)中平衡时循环伏安(CV)曲线明显变得连续且平滑,吡虫啉(IDP)不可逆还原峰电流显著增加。将制备的β-CD-r GO/GCE、MIP/GN/GCE和OCS-GF三种电极作为工作电极,应用于实际糙米样品中烟碱农药的检测。结果表明,β-CD-r GO/GCE具有通用性,对五种烟碱农药均有显著的电催化活性,检出限为0.10~0.11μM。GN/MIPs/GCE在提高烟碱农药检测灵敏度的同时,通过嫁接分子印迹薄膜,提高了烟碱农药的检测特异性,检出限为0.10μM。OCS-GF充分利用了三维石墨烯电极的立体结构,大大扩大了吡虫啉检测的线性范围,使线性范围从GN/MIPs/GCE的0.5μM~15.0μM增加到了1.0μM~50.0μM。此外,针对五种烟碱农药各自的物理化学特性,建立了适用于不同烟碱农药的前处理方法,与新型电化学传感器相结合,回收率达到70%~120%,且与液相检测结果一致,表明在实际样品中的可行性。
[Abstract]:Nicotine pesticide is one of the world's largest pesticide sales, but the long-term abuse and illegal use of lead in agricultural products and low toxicity pesticide residue seriously exceed the standard, cause potential health problems for people as well as the "green trade barrier". China as an agricultural country, need to establish a rapid, sensitive, large-scale field inspection and monitoring technology of neonicotinoid electrochemical technology with low price. The sensor with fast response, portable equipment, low cost, simple operation and other advantages, has gradually become one of the most vigorous means of detection of pesticide residues in the scene. With the rapid development of supramolecular recognition technology, surface molecular imprinting technique and three-dimensional porous material, with the high electrocatalytic activity of graphene with working electrode element application in the electrochemical sensor core, in order to improve the sensitivity and selectivity of the electrochemical detection method, linear range, nicotine An important research direction of the electrochemical detection of pesticide residues, but also a great challenge for analytical workers. Based on this study, the main contents of this paper are as follows: beta cyclodextrin redox Shi Moxi synthesized by using simple synthetic route (beta -CD-r, GO) and on the surface of glassy carbon electrode modified and constructed beta cyclodextrin / graphene based electrochemical sensor. Beta -CD not only as a reduction of graphene oxide (R GO) stabilizer, as well as supramolecular recognition of guest molecules paichongding (IPP), through the formation of supramolecular inclusion and bringing IPP to the graphene surface, thereby enhancing the electrochemical response signal with the bare electrode (GCE.) and graphene modified electrode (R GO/GCE) compared to China's independent research and development of new neonicotinoid paichongding (IPP) in beta -CD-r on GO/GCE irreversible reduction peak current value increased by 14 times and 2 times, significantly increased IPP. In order to further improve the detection sensitivity. The specificity of neonicotinoid pesticides, successfully grafted on the molecular imprinted polymer film on the surface of graphene carrier. The graphene surface molecular imprinted electrochemical sensor constructed significantly improves the electrochemical electrochemical detection of neonicotinoid response signal recognition specificity, shorten the response time. The balance test uses innovative p-vinyl benzoic acid (VBA, with alkenyl unit connected with crosslinking agent and template molecular recognition group and graphene by pi pi interactions and the connection of the benzene ring), Shi Moxi (GN) molecular imprinted monolayer surface successfully loaded uniform (MIPs) film, the graphene surface molecular imprinting polymer preparation of molecularly imprinted membrane (MIPs/GN). The thickness of only 1.9nm, far lower than reported in the literature of graphene surface molecular imprinting film thickness 17nm.GN/MIPs/GCE of imidacloprid imprinted factor at 2.3, significantly higher than that of similar nicotine pesticides, showed good specificity. The -CD-r GO beta and MIPs/GN only modified on the glassy carbon electrode surface, the recognition site is limited, the linear range is narrow, so the chitosan three-dimensional graphene was synthesized by hydrothermal method, increase the effective surface area of the electrode, then build the chitosan oligosaccharide the 3D graphene electrochemical sensor. The effects of ultrasonic stripping frequency of three-dimensional graphene graphene oxide precursor, ultrasonic stripping time, graphene oxide sheet size. Then, based on the characteristics of chitosan oligosaccharide with positive charge, which combined with the negatively charged graphene oxide, preparation of uniform holes, shell the structural stability of the modified oligosaccharide three-dimensional graphene. Compared with three-dimensional graphene modified chitosan, three-dimensional graphene electrode in phosphate buffer solution (PBS) CV at equilibrium (CV) curve became flat and continuous Slide, imidacloprid (IDP) irreversible reduction peak current increased significantly. The preparation of beta -CD-r GO/GCE, MIP/GN/GCE and OCS-GF three electrode as the working electrode, applied to the actual detection of nicotine pesticides in brown rice samples. The results showed that beta -CD-r GO/GCE is universal, the electrocatalytic activity of five kinds of pesticide nicotine significantly have a detection limit of 0.10~0.11 M.GN/MIPs/GCE in improving the detection sensitivity of nicotine pesticides at the same time, by grafting the molecularly imprinted film, improve the detection specificity of neonicotinoid, a detection limit of 0.10 M.OCS-GF make full use of the three-dimensional structure of graphene electrode, greatly extends the linear range of detection of imidacloprid, the linear range from GN/MIPs/GCE 0.5 mu M~15.0 mu M to 1 mu M~50.0 mu M. in addition, according to the physical and chemical properties of five kinds of pesticide nicotine respectively. The pretreatment method was established for different nicotine pesticides, and new Combined with the electrochemical sensor, the recovery rate is up to 70%~120%, which is consistent with the liquid phase detection results, indicating the feasibility in the actual sample.
【学位授予单位】:哈尔滨工业大学
【学位级别】:博士
【学位授予年份】:2017
【分类号】:O657.1;TP212.2;TQ450.263
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