Rapid Detection Of Small Organic Molecules In Pesticide Residue Based On Gold Nanoparticles

“Agricultural country”,has always been a label of our country.In other words,Agriculture is the foundation of other areas,so the development of agriculture is extremely important.Pesticides,as the necessities of agriculture,is an indispensable part of agriculture.Our country has become one of the great powers in pesticide production and consumption from 1990 s.In order to meet the needs and requirements of agriculture,the types of pesticides are also increasing.However,the damage bringing to the environment and human is also increasingly prominent due to the abuse and unreasonable use of pesticides.The pesticide residue in human daily life necessary such as water,crops,vegetables and fruits are harm to human health.For the pace of life so efficient and fast rhythm in today and facing the sudden and diversity of problem,can or not fast,convenient and real-time detection of small organic molecules in pesticide residue,it has important practical significance for the safety of the ecological environment and human health.For the detection of small molecules of pesticides,it is common to use large apparatus such as chromatograph.But,all of them need complicated sample preparation and professional operators,expensive and time-consuming and laborious at the same time.However,the change of size and morphology of the noble metal,especially gold nanoparticles,will bring different optical phenomena and macroscopic appearance.Based on the unique optical properties,gold nanoparticles(AuNPs)are widely used in the field of rapid detection.In this thesis,two kinds of detection based on gold nanoparticles were developed to rapid and accurate detection of glyphosate(GPS)and triazophos(Trs).The research content includes two parts as follows:1)Rapid colorimetric detection of GPS based on gold nanoparticles.In view of the glyphosate which is the largest use of pesticides,this section presents a new detection system: A certain amount of lead ions can cause the aggregation of AuNPs and the color of the solution will change in the meantime.However,once there is glyphosate in the gold nanoparticles,it will prevent the aggregation of gold nanoparticles because of the easily chelating between glyphosate and lead ions,so,this will complete the rapid colorimetric detection of glyphosate.The method about detection of glyphosate has good selectivity and anti-interference.The limit of detection is 0.5?M by naked eyes and 2.38 nM by UV-vis spectroscopy.At the same time,the detection mechanism also has very good practical applicability and feasibility in actual water samples.2)Rapid colorimetric detection of Trs based on gold nanoparticles.In this work,a new mechanism,without adding any additives,which can directly fast and easy detection of triazophos is proposed: After protonation of triazophos at the acidic conditions,due to the presence of sulfur and nitrogen in the triazophos,so the triazophos can connect to the surface of gold nanoparticles through the formation of Au-S bonds.The triazophos are interconnected by hydrogen bonding.So that,the gold nanoparticles can aggregate.The color of the solution changes from wine red to bluish violet and the optical properties of gold nanoparticles also change correspondingly.Thus,The limit of detection is 0.5?M by naked eyes and 0.078?M by UV-vis spectroscopy.Furthermore,the AuNPs-based optical probe for triazophos has shown excellent electivity and anti-interference.That can be well to meet the sensitivity and effectiveness in the practical application.