Preparation And Application Of Aminopyralid Molecularly Imprinted Polymer

Because of its low toxicity,aminopyralid has been used more and more widely in recent years.However,its high residue will not only damage crops,but also harmful to the human.Because the matrix of crops is complex,it is necessary to choose proper pretreatment method to detect the target substance.Molecular imprinting technique?MIT?is the principle of simulating"enzyme-substrate"and"lock-key",It can extract,separate and enrich trace target from complex matrix,and has good selectivity and specificity.The prepared molecularly imprinted polymer?MIP?can be used as a filler in solid phase extraction?SPE?,and a magnetic nano-molecularly imprinted polymer?MMIP?can be prepared by magnetic nanotechnology and used in dispersed solid-phase extraction.In this paper,aminopyralid was used as the target substance,mainly from the preparation of aminopyralid molecularly imprinted polymer,the preparation and application of aminopyralid molecularly imprinted solid phase extraction column,the preparation of magnetic molecularly imprinted polymer of aminopyralid and the application of dispersible solid phase extraction to study.The specific content and results are as follows:1?According to the structure of aminopyralid,picloram was chosen to used as the dummy template,and the polymerization system was optimized.Based on the amount of adsorption,4-vinylpyridine was selected finally as the functional monomer,Trimethylolpropane trimethacrylate as the cross-linker,and methanol as the porogen.The aminopyralid molecularly imprinted polymer was prepared using precipitation polymerization.It was characterized by scanning electron microscopy and infrared spectroscopy,ect;the study on specificity of the polymer and its binding mechanism were carried out by dynamic and static experiments and the analysis of Scatchard equation;the class specificity of MIP was also studied.The results showed that the MIP had two types of binding sites,the maximum binding amount was 1171.8?g/g and3022.5?g/g,respectively,and the MIP was class-specific to the pyridine carboxylic acid,the adsorption amount all reached 80%,the imprinting factor IF all greater than 1.The MIP was applied in solid phase extraction,the conditions of MI-SPE were optimized,and the MI-SPE-LC-MS/MS method was established and used to detect the amount of aminopyralid in milk.The methodological evaluation results showed that the limit of detection of this method was 0.124?g/L,and the limit of quantification was 0.412?g/L,the linearity was good in 1¹00?g/L,and the correlation coefficient was r²=0.9982.At the three levels of addition,the average recovery of aminopyralid was 83.6%with the relative standard deviations of less than 11.4%?n=3?.The recovery of the three other pyridine carboxylic acid herbicide were all greater than 75%.2?Fe₃O₄@SiO₂-NH₂@MIP,Fe₃O₄@SiO₂-COOH@MIP two kinds of aminopyralid magnetic molecularly imprinted polymers?MMIPs?were prepared on the surface of magnetic nano-molecules by synthesizing surface-modified magnetic carriers with amino and carboxyl groups and surface molecular imprinting technique.The morphology and magnetic properties of the polymer were characterized by infrared spectroscopy,transmission electron microscopy,and vibrating sample magnetometer.The results show that Fe₃O₄@SiO₂-NH₂@MIP has good dispersibility and good magnetic properties.The adsorption performance was evaluated,and the results show that Fe₃O₄@SiO₂-NH₂@MIP is better than Fe₃O₄@SiO₂-COOH@MIP.The kinetics,isothermal adsorption test and Scatchard equation of Fe₃O₄@SiO₂-NH₂@MIP showed that MMIP has the characteristics of surface molecular imprinting.It has large specific surface area,fast mass transfer rate.The adsorption amount is obviously higher than that of common molecularly imprinted polymer,and maximum apparent binding amounts were 2737.74?g/g and 4223.55?g/g,respectively.The dispersed solid phase extraction conditions were optimized and combined with LC-MS/MS for the detection of aminopyralid in milk.The results showed that the detection limit was 0.231?g/L and the limit of quantification was 0.77?g/L.At the three levels of addition,the average recovery of the target was 86.9%,and the recovery of the other three pyridine carboxylic acid pesticides was greater than 78.2%.