Preparation And Application Of Xi Caojing Molecularly Imprinted Microspheres

Tobacco is one of the important economic crops for our country,which plays a prominent role in economic development and increasing national fiscal accumulation.Triazine herbicides has important role in the reducing cost and improving quality of tobacco.However,the use of herbicides in agriculture endangers human health with causing environmental and crops pollution.Therefore,it is necessary to detect the triazine herbicide residue in tobacco.The aim of this work is to develop a new sample pretreatment method to extract triazine herbicide residues from tobacco by using molecular imprinting technology.A molecularly imprinted matrix dispersive solid phase extraction-UPLC-MS/MS method for detection of triazine herbicides in tobacco was established.The specific contents are as follows:(1)The imprinting system(simetryn or atrazine as template)was designed at the wb97xd/def2 tzvp level based on density functional theory,and the interaction of template with monomer was computed in each binding sites.The results showed that methacrylic acid was the most suitable monomer for these imprinting systems,and the main interact between template and monomer was through hydrogen bond.In addition,the thermodynamic process of self-assembly(template with monomer)was discussed,which provided reference for the control of polymerization conditions.(2)According to the results of theoretical calculations,simetryne imprinted nanoparticles were synthesized using SMT as template,methacrylic acid as functional monomer,acetonitrile as solvtion by precipitation polymerization.The effect of solvent dosage,polymerization time and stirring for SINs size,distribution and imprinting factor were investigated.At the best conditions,we obtained high selectivity and good monodispersity SINs.The maximum adsorption capacity of SINs was obtained by static adsorption experiment,and the adsorption process of SINs was analyzed by Scatchard model.Combined with theoretical calculation results,there were two kinds adsorption sites in SINs,and the interaction worked through a single hydrogen bond and a double hydrogen bond.The selective adsorption experiments showed that the synthesized SINs had selective adsorption capacity for simetryn and the analogues.(3)Using the synthesized SINs as adsorbent,the triazine herbicide residue in tobacco was separated and purified by matrix dispersed solid phase extraction.Through optimizing solid phase extraction conditions and UPLC-MS/MS detection parameters,a method of molecularly imprinted matrix dispersive solid phase extraction UPLC-MS/MS for detection of 4 triazine herbicide residues in tobacco was established.The low detection limit was 6-30ng/g and the recovery rate was 80-125%.This method can be used in analysis of multiple triazine herbicide residues in tobacco.