QCM Sensor Based On Molecular Imprinting Technology For Remote Monitoring Of Pesticide

The application of pesticides is very extensive in production and life. Relevant statistics show each year there are about 2 million people around the world getting sick because of pesticide pollution. Sewage emissions exceed the standard of pesticide industry, pesticide improper prohibited in greenhouse vegetable and use of high toxic pesticides caused great threat on environmental safety and human health,which has become a major social problem to be solved. Since traditional means most require expensive equipment, complex operation, and need large amounts of organic solvents for pretreatment, they cannot realize real-time monitoring of pesticides. At present, the market urgently needs to realize the industrial wastewater, food production and processing areas, methods of pesticide production and application field of pesticide remote inspection. So the study on without sample pretreatment,simple, fast, real-time detection method has very important significance to the supervision and inspection of pesticides in water and spraying process. This paper proposed the ideas and methods of monitoring system for detection of pesticide field for the first time. The molecular imprinted polymer(MIP) has the advantages of simple preparation, easy separation and good specificity; as detection means, quartz crystal microbalance(QCM) are ultrasensitive, unmarked and can realize real-time online detecting; the most commonly used organophosphorus pesticide chlorpyrifos(CPF) as the template molecule. The sensor with high specificity and high sensitivity was prepared without sample pretreatment and could directly detect the greenhouse spray in aqueous phase. The design purpose was to achieve the implementation of pesticide pollution sources and the implementation of remote monitoring and control.The research contents and results include the following three aspects:1. CPF EC was taken as the template molecule, pyrrole as functional monomer,phosphate buffer solution(PBS) as solvent to prepare CPF molecularly imprinted polypyrrole(PPy) modified QCM sensor by electrochemical polymerization. The preparation conditions of the sensor were optimized. The properties and surfacemorphology of PPy-MIP film were characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS), static water contact angle(WCA),QCM, scanning electron microscopy(SEM) and atomic force microscopy(AFM)respectively.2. The sensor was used for determination of CPF in aqueous solution. The detection limits of the sensors simultaneously prepared were 1.11 ppm and 1.55 ppm.The specificity, temperature stability, the actual sample testing and regeneration performance of the sensor were analyzed. Detection indicated that imprinted sensor response to CPF EC was specific recognition of molecules; the detection results was little affected by temperature; the sensor can detect CPF in complex matrix(the vegetable juice); the recovery rate range was from 92% to 104%; the relative standard deviation(RSD) was 4%; the sensor could be recycled 13 times. In addition,exerting DEP in the detection of CPF EC in aqueous solution was explored for the enrichment of CPF latex particles to accelerate the recognition rate and reduce the detection limit.3. CPF imprinted sensor of PPy was used to determine CPF spray at first. The result showed the frequency response value and concentration of pesticides had no linear relationship and specificity is not good. Then, we chose highly hydrophobic polyvinylidene fluoride(PVDF) as film-forming material to prepare PVDF-CPF imprinted sensor. The determination of pesticide spraying is specific but has not yet reached the expected effect. The silicone insulating paint was chosen as the film-forming material. From the water contact angle increase and a large number of micron and submicron grooves in the SEM images, the film probably has a kind of hydrophobic structure like lotus leaf. The change of resonance frequency in the process of identifying jagged, which may be caused by imprinted sites embedding and air in the groove.