Determination Of 27 New Fungicides Pesticide Residues In Cereals,Vegetables And Fruits By Liquid Chromatography –tandem Mass Spectrometry And Liquid Chromatography Coupled With Quadrupole-time Of Flight Mass Spectrometry

Pesticides play a significant role in improving crop yields,but excessive use of pesticides can lead to pesticide residues in agricultural products that are harmful to food safety and human health.Therefore,the detection of pesticide residues is a hot topic in recent years.Strobilurin and succinate dehydrogenase inhibitors fungicides are the latest two kinds of fungicides.They have the characteristics of low toxicity,high efficiency and broad spectrum.In order to improve the efficacy of fungicide,solve the resistance problem of a single fungicide in the process of the growth of crops,we usually sprayed crops with different kinds of fungicides,which are mixed at various ratios.At present,the detection of new fungicides in cereals,vegetables and fruits is mostly limited to the detection of a single species,the lack of detection of complex fungicides,and the simultaneous detection of the same kind of fungicides,which can not effectively distinguish between the same body of the fungicide.Therefore,it is very meaningful to establish pesticide detection,screening and confirmation methods for new fungicides in cereals,vegetables and fruits.In this paper,an analytical method for simultaneous determination of 27 new fungicides in cereals,vegetables and fruits was established for the first time.The thesis is divided into three chapters,the main contents are as follows:1.The existing sample preparation technology and detection methods of pesticide residues are reviewed.In this paper,the principle and application of solid phase extraction,solid phase microextraction,dispersed solid phase extraction,supercritical fluid extraction,dispersion liquid microextraction,accelerated solvent extraction,microwave assisted extraction,gel permeation chromatography,stirring adsorption and QuEChERS technology are introduced.Secondly,it introduces the application of chromatography and mass spectrometry detection means in cereals,vegetables and fruits.At the same time,the background and purpose of this parper are expounded.2.A method for simultaneous determination of 27 new fungicides in cereals,vegetables and fruits using DSPE-LC-MS/MS technique was developed.Samples were extracted with acetone containing 1%(v/v)acetic acid,purified by a mixed sorbent of ethylenediamine-N-propylsilane(PSA),C18,anhydrous magnesium sulfate(MgSO4),and Multi-walled carbon nanotubes(MWCNT),separated by a reversed phase C18 column,gradiently eluted with acetonitrile and 0.1% formic acid solution(Containing 5 mmol/L ammonium acetate).Anhydrous magnesium sulfate was used as a dewatering agent.The positive ion modes and multiple reaction monitoring(MRM)mode were used in the analysis,and the analytes were quantified by external standard method.The 27 fungicides showed good linearities in the range of 0.02-200 ?g/L,and the limits of detection(LOD)and the limits of quantification(LOQ)were 0.006-16.67 ?g/kg and 0.02-55.5 ?g/kg,respectively.The linear relative coefficients was greater than 0.995.The recoveries were in the range 70.02%-117.6% and the relative standard deviations(RSD)were ranged from 0.01% to 19.62%(n=3).The method has the advantages of simplicity,rapidity,high sensitivity and better purification effect.It is suitable for the rapid determination of the common fungicides in cereals,vegetables and fruits.3.A method for simultaneous determination of 27 new fungicides in cereals,vegetables and fruits using SPE-LC-Q-TOF/MS technique was developed.Samples were extracted with acetonitrile containing 1%(v/v)acetic acid,purified by solid phase extraction(SPE)with a Crabon/NH2 cartridge,eluted with acetonitrile-toluene(3:1,v/v),separated by a reversed phase C18 column,gradiently eluted with acetonitrile and 0.1% formic acid solution(Containing 5 mmol/L ammonium acetate),determined by LC-Q-TOF/MS and quantified by external standard method.A data base of the accurate mass numbers and a library which contains the 27 fungicides were established.The automatic retrieval of detection results was carried out according to the characteristics of the compounds,such as accurate mass,retention time,isotope peak distribution,isotopic ratios,and so on.Based on the above results,the qualitative identifications of the 27 new fungicides were accomplished without the contrast of standard substances.The results indicated that 27 new fungicides showed good linearities in the range of 0.02-300 ?g/L,and the limits of detection(LOD)and the limits of quantification(LOQ)were 0.01-20 ?g/kg and 0.02-100 ?g/kg,respectively.The linear relative coefficients were greater than 0.995.The recoveries were in the range 71.8%-114% and the relative standard deviations(RSD)were ranged from 0.1% to 21.3%(n=3).The method has the advantages of simplicity,rapidity and high sensitivity.It is suitable for the rapid determination of the common fungicides in cereals,vegetables and fruits.