Synthesis Of Chlorsulfuron Molecularly Imprinted Polymer And Its Application In The Analysis Of Pesticide Residues In Tobacco Leaves

With the development of society and the continuous improvement of living standards,people are increasingly concerned about smoking and health issues.The safety of tobacco leaves is closely to the use of pesticides.Tobacco with pesticide residues burning will harm to humans health and the environment.It is an important means to control the excessive peasants which detect the tobacco residues efficiently and quickly.The sulfonylurea herbicides are widely used in the prevention and control of annual or perennial weeds due to their characters of high herbicidal activity,broad spectrum and low toxicity in the environment.It is overuse caused a series of pesticide residues.Pretreatment become the bottle neck of analysis of sulfonyreas because the residues are very low and sample matrixs are very complex.We have established the methodology of sulfonylurea herbicides with highperformance liquid chromatography(HPLC).In this study,the chlorsulfuron molecularly imprinted polymer microspheres(CS-MIPMs),with high selectivity and affinity,were synthesized using CS as the template.The morphology,structure and properties of the polymer were characterized by scanning electron microscopy(SEM),infrared spectroscopy(FT-IR)and thermogravimetric apparatus(TGA).and the affinity and selectivity of the polymer were evaluated by equilibrium adsorption experiment.A molecular imprinting polymers solid phase extraction(MISPE)were developed for screening of six sulfonylurea herbicides in tobacco samples including CS,metsulfuron-methyl(MSM),bensulfuron-methyl(BSM).tribenuron-methyl(TBM).ethametsulfuron(EMS)and nicosulfuron(NS),and analysis with HPLC for quantification.The results have indicated that the method developed is easier,faster,and has better purification effect.It has also demonstrated that this multiresidue analytical method can meet the requirements for the simultaneous determination of many sulfonylurea herbicides in tobacco samples.The major topics in the thesis include:(1)The CS-MIPMs were synthesized by precipitation polymerization using CS as the temp late,α-methacry lic acid(MAA)as the functional monomer,and trimethylolpropane trimethacrylate(TRIM)as cross-linker,2,2-azobisisobutyroni-trile(AIBN)as the initiator and dichloromethane as the porogenic and solvent.(2)The morphology,structure and properties of the polymer were characterized by SEM,FT-IR and TGA.SEM showed that CS-MIPMs had a porous structure.FT-IR showed that we have successfully prepared CS-MIPMs,then eluted down it in the elution process.The TGA showed that the prepared CS-MIPMs and blank imprinted polymer microspheres(NIPMs)had good stability which is suitable for HPLC analysis.(3)The results of the equilibrium adsorption experiments show that the adsorption of CS-MIPMs is the best in acetonitrile.The results of the equilibrium adsorption experiments and the Scatchard analysis showed that the CS-MIPMs had a good retention effect on template molecules,and CS-MIPMs with MAA as functional monomers can form two types of binding sites by hydrogen bonding.The binding behaviors of the template CS and its analogues on CS-MIPMs were evaluated by equilibrium experiments,which showed that the CS-MIPMs has specific affinity for the CS.(4)Solid-phase extraction(SPE)with the CS-MIPMs as an adsorbent was used to pretreat CS residues in tobacco samples,then the concentration of CS was detected by high performance liquid chromatographic(HPLC).Its best solvents for loading,washing and eluting process of CS molecularly imprinted polymer solid-phase extraction(CS-MISPE)were obtained.Thus,a detection technique for CS residues in tobacco was developed using CS-MISPE as pretreatment method and HPLC as an analytical tool.The peak area and concentration showed good linearity in the concentration range of 0.10～20mg/L with a linear correlation coefficient>0.999.and the RSD was 3.49～6.88%,LOD was 0.13μg/g.The average recoveries of CS residues in tobacco at three spiked levels(0.25μg/g.0.50μg/g,1.00μg/g)ranged from 83.04%to 97.78%.(5)The pretreatment methodology of purification and preconcentration of 6 sulfonylurea herbicides.including CS.MSM,BSM,TBM,EMS and NS in spiked tobacco samples were developed using CS-MISPE cartridges prepared by using theCS-MIPMs as the sorbent,and analysis with HPLC for quantification.The results of 6 sulfonylurea herbicides showed in tobacco samples were satisfactory.The linear corrlation was 0.9993～0.9999 among concentrations range of 0.10～20mg/L.Recoveries from tobacco samples spiked with six sulfonylurea herbicides at spiking levels ranging from 0.50~50μg/g were from 77.60～102.05%,with RSD was 0.16～7.07%,LOD was from 0.08μg/g to 0.46pg/g.