| Carbamate pesticides are common pesticides,which are toxic and carcinogenic,and can cause harm to the human nervous system and life at a certain dose.They are found in various common agricultural products.How to determine formate pesticides in food efficiently and accurately are particularly important.This thesis mainly uses magnetic covalent organic framework materials to carry out magnetic solid phase extraction of carbamate pesticides in food,combined with ultra performance liquid chromatography tandem mass spectrometry to develop analytical method for a new type of carbamate pesticides in food.Based on the structural characteristics of carbamate compounds,the thesis designs and synthesizes a new type of magnetic covalent organic framework material(Fe3O4@COFs(Tp-TAPM)),and uses the material for magnetic solid phase extraction.The research uses transmission electron microscope,scanning electron microscope,Fourier transform infrared spectroscopy,powder X-ray diffraction to characterize the developed materials.In addition,the material is analyzed and tested for thermogravimetry,specific surface area,porosity and contact angle.The experimental results show that the material is wrapped to form a sphere and has a uniform particle size(3 10 nm)large specific surface area(81.72 m2/g),small porosity(0.0227 cm3/g)and good hydrophilicity(33.1°)with good stability at the temperature range from 0 to 455℃.The synthesized magnetic material has good physical and chemical properties and can be used as a potential sample pretreatment adsorption material.Based on the Fe3O4@COFs(Tp-TAPM)extraction material,this work establishes a determination method using liquid chromatography tandem mass spectrometry(HPLC-MS/MS)for 9 carbamate pesticides in fruits and vegetables.The thesis first investigats the adsorption behavior of the material.The material shows high adsorption capacity.The maximum adsorption capacity is 30.3-60.5 mg/g.The adsorption rate is fast,and the adsorption equilibrium can be reached within 15 min.It can be used repeatedly,and it is easy to regenerate.This material is successfully used for the enrichment and detection.The linear range of 9 pesticides is 0.1-100 μg/L,the correlation coefficient is greater than 0.99.The method has high sensitivity(0.02 μg/L),low detection limit(0.02-0.15 μg/L),and the method has good reproducibility.The recovery of standard addition at the three concentration levels(low,medium and high)is 80.31-118.95%.Finally,this thesis uses Fe3O4@COFs(Tp-TAPM)magnetic solid phase extraction as the sample pretreatment material,and develops a chromatographic tandem mass spectrometry quantitative method for analysis of phenolic substances in fruit juice and tea samples.The linear range of analytical method for 5 kinds of phenolic compounds is 0.1-100 μg/L,and the correlation coefficient is greater than 0.99,the detection limit is 0.06-0.18 μg/L,and the quantification limit is 0.17-0.30 μg/L.The results also shows that the intra-day and inter-day precision are 2.1-5.7%and 3.2-7.5%,respectively.The recoveries of spiked sample at low,medium and high level are between 80.18%and 105.67%. |
