Molecularly Imprinted Solid Phase Extraction Detection Technology And Application Of Triazine Pesticide Residues In Tobacco Leaves

Using triazine herbicides in the process of tobacco production on the one hand can reduce costs,on the other hand can improve tobacco yields and quality.However,due to their chemical stability,triazine herbicides are easy to persist in plants and the environment at trace level for a long period.Besides,triazine herbicides have the bad effect of disturbing the human endocrine system and reproductive system.During the process of establishing an analytical method for the triazine herbicides residues,and the quality of the pretreatment influences the final results directly.The conventional pretreatment methods currently used for triazine herbicides are generally nonselective and have not been applied to tobacco matrix.In this paper,a pretreatment method of Molecularly Imprinted Solid Phase Extraction(MISPE)with high selectivity for triazine herbicides in tabacco was established.The main contents of this paper are as follows:(1)The types and volumes of suitable polymerization solvents were explored by preparing Nonimprinted Polymers(NIPs).(2)Molecularly Imprinted Polymers(MIPs)was synthesized by bulk polymerization method,with atrazine as the template molecule,methacrylic acid(MAA)as the functional monomer,ethylene glycol dimethacrylate(EGDMA)as the crosslinker,azobisisobutyronitrile(AIBN)as the initiator.Two different kinds of MIPs were prepared using acetonitrile and toluene as the polymerization solvents respectively.Besides,the two MIPs were characterized by scanning electronic microscopy,fourier transform infrared spectroscopy,thermal gravimetric analysis and mercury porosimetry.The results showed that the obtained MIPs are porous,and the template molecules were successfully imprinted in the polymer.Besides,MIPs have good thermal stability below 300?.(3)Binding capacity of the two MIPs were studied.MIPs showed the greatest binding capacity when the adsorption solvent was the same as the polymerization solvent.The binding capacity of the MIPs obtained with toluene as the polymerization solvent are much larger than that of MIPs obtained with acetonitrile as the polymerization solvent at the same adsorption concentration.In contrast,the slectivity of MIPs obtained with acetonitrile as the polymerization solvent is better than that of MIPs obtained with toluene as the polymerization solvent.(4)The atrazine MIPs obtained with toluene as the polymerization solvent were packed in empty solid phase extraction(SPE)columns.And Molecularly Imprinted Solid Phase Extraction(MISPE)technique was used to pretreat twelve triazine herbicide residues in tobacco.The best solvents found for washing and eluting steps were toluene and dichloromethane:acetic acid=4:1(V:V),respectively.(5)An MISPE-HPLC analytical method for the determination of six triazine herbicides residues in tobacco was established,with mean recoveries of 74.71%-110.70%,detection limit between 0.125 ?g/g and 0.47 ?g/g and relative standard deviations(RSDs)between 5.6%and 14.8%(n= 3).