| With the improvement of economic living standards,the consumption of fruits and vegetables is increasing day by day.In order to increase the yield and control pests and diseases,the farmers have begun to use a wide range of pesticides without the variety and efficacy.This has led to the safety risks in fruits and vegetables.What's more,with the improvement of living standards,people's requirements for food quality have been continuously improved,and food safety issuesare getting more and more attention.This has prompted countries to continuously introduce more stringent standards for pesticide residue limits of agricultural products.In recent years,various scientific researchers have continuously innovated methods for detecting pesticide residues,and pesticide residue detection technology has also been greatly improved.However,there are still some problems to be improved.It is urgent to finda high sensitivity,simple operation,fast and accurate pesticide residue detection method.In 2003,Professor Anastassiades of the US Department of Agriculture developed a quick,easy,cheap,effective,rugged,and safe(QuEChERS)sample preparation method that is increasingly used in pesticide residue detection.Based on the traditional sample pretreatment method,people continue to innovate in order to improve the efficiency,sensitivity and accuracyof detecting pesticide residues.At present,sample pretreatment technology is developing in a fast and accurate direction.People use high-efficiency,high-accuracy processing to ensure the reliability of test results.Magnetic nanoparticles are emerging nanomaterial.It has special magnetic properties,surface effects,and adsorption properties.When the magnetic nanoparticles are used in the pretreatment process,the special magnetic properties and the external magnetic field can be used to quickly separate the impurities from the sample solution,eliminating the steps of centrifugation and filtration.So it can improve the purification efficiency.In this paper,a method based on the properties of magnetic nanomaterials with modified QuEChERS technologyand gas chromatography-tandem mass spectrometry(GC-MS/MS)for the detection of pesticide residues in fruits was established.The main research contents and conclusions are as follows:1.Using apple as raw material,the extraction and purification conditions were optimized.Magnetic nanoparticles(MNPs)were added during the pretreatment process,and the interfering substances were adsorbed under the action of an external magnetic field to promote the stratification of the extract,instead of the centrifugation step in the conventional method.These all contributed to improve the pretreatment speed and the purification effect.2.The experimental conditions for the detection of 69 pesticide residues by gas chromatography-tandem mass spectrometry(GC-MS/MS)were optimized.The experiment use external standard method to quantify,and the linear coefficient coefficient isR~2>0.990,and the linear relationship is good.The limits of detection(LOD)is 0.06?g/kg~2.12?g/kg,and the limit of quantitation(LOQ)is 0.20?g/kg~7.06?g/kg.3.Recoveries were evaluated in two represetantive matrices(apple and pear)with the spiked concentrations of 10?g/kg,50?g/kg and 100?g/kg.The recoveries of 69 pesticides ranged between 70.03%-120.00%at the addition of10?g/kg,50?g/kg and 100?g/kg.The relative standard deviation(RSD)was less than 14.87%.4.The apple and pear actual samples were tested by the experimental method and the national standard method“GB 23200.8-2016 Detection of 500 pesticides and related chemical residues in fruits and vegetables by gas chromatography-mass spectrometry”.The results obtained by the two methods were basically the same.The national standard method is not only complicated but also takes a long time.5.Screening 69 pesticide residues in actual samples of apples and pears in Taian,and we didn't detect excessive pesticide residues,which indicating that the pesticide residues of apples and pears in the city are ideal. |
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