Development Of Rapid Detection Instrument For Pesticide Residues In Vegetables Based On Enzyme Immunosensor

Vegetable quality and safety is vital to the health of the people and the sustainable&healthy development of the vegetable industry.In order to ensure the quality and safety of vegetable products,it is necessary to strictly control the use of pesticides in vegetable production process.The traditional analytical instruments have a long detection cycle and cannot achieve rapid detection on site.At present,the principle of enzyme inhibition is the mainstream method for rapid detection of pesticide residues in China.However,such instruments with low sensitivity are prone to false-positive and false-negative problems,and some detection limits of pesticide residues cannot meet the international or domestic minimum detection standards,which is not conducive to on-site rapid detection.At present,there is an urgent need to develop a rapid screening technology for pesticide residues in vegetables so as to realize on-site and rapid detection of pesticide residues,effectively monitoring the rational use of pesticides and reducing the economic losses caused by excessive pesticide residues in vegetables.In order to establish a rapid and accurate method for the determination of pesticide residues,the main contents of this paper are as follows:（1）Acetylcholinesterase biosensor based on GO-CS/AuNSsIn this experiment,acetylcholinesterase used as bio-recognition element,chitosan with good biocompatibility and strong adhesion used as dispersant,an enzyme biosensor with good electron transfer and large specific surface area was prepared using excellent conductivity of graphene oxide and nano-gold cage,which improved the sensitivity and stability of detection.The detection limit of chlorpyrifos was 0.003μg/L.The recovery of chlorpyrifos was between 94%and 103%,and the relative standard deviation was between2.8%and 5.5%.（2）Electrochemical Immunosensor Based on Fe₃O₄-CS/MWNTsIn this experiment,antibodies used as bio-recognition elements,magnetic ferroferric oxide nanomaterial with catalytic activity of artificial mimic enzyme and high specific surface area adsorbing functional molecules used as a carrier,and chitosan used as dispersant improving dispersibility and biocompatibility,multi-walled carbon nanotubes with high conductivity and large surface area used as a support,an electrochemical immunosensor was prepared which pesticide antibodies was effectively immobilized and the detection signal was amplified.Chlorpyrifos as an object,the detection limit of was 0.008μg/L and the recovery rate was between 95%and 103%in the standard-added recovery detection of actual samples.（3）Development of rapid detection instrument for pesticide residues based on enzyme immunosensorA rapid detection instrument of pesticide residues based on an enzyme-immune sensor was developed by combining technology of enzyme sensors and immune sensors in this project.A screen-printed electrode was adopted instead of ordinary electrodes to simplify related operations.At the same time,it was conducive to the miniaturization of testing equipment by improving the hardware and software.The detection data can be uploaded to the Internet of Things for Vegetable Quality and Safety Detection in real time,which realizes the rapid and online detection of pesticide residues in vegetables.The detector has the advantages of high sensitivity,simple operation,less reagent consumption,miniaturization and real-time detection on site.The above-mentioned research provided theoretical guidance and technical support for the development of rapid detection technology for pesticide residues.