Study On Fluorescent Sensor Based On Quantum Dots Detection Pesticide Residues

Agriculture is one of the most important components of China’s economy.With the modernization of agriculture,the use of pesticides is becoming more and more extensive,which leads to environmental problems and food safety problems are becoming more and more prominent。Therefore,it is very important to establish a fast,efficient,simple and reliable method of agricultural residue inspection.Fluorescence detection has been a hot topic in the field of analysis and detection because of its simple operation,short response time,strong selectivity and low cost.In this paper,three fluorescent sensor systems for the qualitative and quantitative detection of pesticides in food were explored.The research contents are as follows:（1）Au NCs was prepared with GSH as protective agent.The Au NCs fluorescence can be quenched by thiocholine generated by ACh E catalyzed ATCI hydrolysis.Fluorescence sensor was constructed to detect propobromide phosphorus qualitatively and quantitatively.The influence of ACh E concentration,ATCI concentration,p H value,reaction temperature and reaction time on the sensor was investigated.Under optimal conditions,the sensor has a good linear range of 0-0.6mg/L（R²=0.9986）,and the limit of detection of 0.073mg/L.The sensor has good stability and selectivity in actual sample testing.And the sensor has a good recovery rate（97.55%-103.67%）.It provides a new idea for the determination of organophosphorus pesticides in practical application.（2）The synthesis of Zn O QDs based on zinc acetate and urea.The quantum dots are easily quenched by copper ions,and the thiocholine produced by ATCh hydrolysis catalyzed by ATCI can react with Cu²⁺to restore the fluorescence of Zn O QD.Therefore,Zn O QDs/Cu²⁺fluorescence sensor was constructed to detect dichlorvos qualitatively and quantitatively.The influences of Cu²⁺concentration,ACh E concentration,ATCI concentration,p H value,reaction temperature and reaction time on the reaction system were investigated.Under optimal conditions,the sensor has a good linear range of 0-0.14mg/L（R²=0.9986）,and the limit of detection of 0.0091mg/L.The construction of Zn O QDs/Cu²⁺sensor has good anti-interference ability to common substances.The sensor is applied to dichlorvos in potatoes and apples,and a good recovery rate（97.21%-104.45%）is obtained.It is proved that this method has a good prospect in the rapid detection of organophosphorus pesticides.（3）CDs were prepared by hydrothermal method with trisodium citrate and GSH.Using the IFE effect between CDs and Au NPs to construct CDs/Au NPs fluorescence sensors.The effects of Au NPs volume,p H value and reaction time on the sensor were investigated.Under the best experimental conditions,the linear range is 1-20mg/L（R²=0.9981）,and the theoretical detection limit is 0.31mg/L.This method has good anti-interference ability to common pesticides.The sensor is applied to deltamethrin in potatoes and apples,and a good recovery rate is obtained（98.89%-104.08%）.This method has potential value in the practical detection of pyrethroid pesticides.