Preparation And Application Study Of Molecularly Imprinted Polymeric Materials For Phenylurea Pesticides And Multiclass Pesticides

Molecular imprinting technology is a polymer synthesis technology which has a predetermined recognition ability for target molecule.The stable physical and chemical property,preparation simpleness and low cost of molecularly imprinted polymers have led to their applications in many fields such as chromatographic separation,solid phase extraction,sensors,mimic enzyme catalysis,membrane separation.Molecular imprinting technology was applied to the study,the magnetic molecularly imprinted polymers（MMIP）were prepared by precipitation polymerization and suspension polymerization using one or more categories of pesticides as template molecules,the imprinted polymers used as molecularly imprinted solid phase extraction materials.The imprinted polymer materials were characterized by scanning electronic microscopy（SEM）and infrared spectroscopy （IR）,and the materials were used to separate and determine phenylurea and multiclass pesticide residues in foods.It has obvious advantages over the common solid phase extraction technology,which is mainly embodied in good separation enrichment effect,strong specificity and repeated use.Taken nanoparticles Fe₃O₄as magnetic carrier,and difenoxuron as template molecul-ar,α-methacrylic acid（MAA）as functional monomer,cetonitrile as porogen,magnetic molecularly imprinted polymers were prepared by precipitation polymerization.The ultraviolet spectroscopy was used to select the optimal functional monomer MAA and the optimal orifice agent acetonitrile.The performances of the polymer microspheres were characterized by static adsorption test,dynamic adsorption test and scanning electron microscope（SEM）.The polymer microspheres were used as solid phase extraction materials to enrich,separe and cleansing phenylurea pesticide residues in samples,and the samples were determined by high performance liquid chromatography（HPLC）.The results showed that the pretreatment method was simple and fast,and had the strong adsorption capacity for phenylurea pesticide and good cleansing effect for samples,Complete sparation of the pesticides was achieved within 20 min,the average recoveries were 82.4%～97.3%,the relative standard deviations（RSDs）were between 1.25%and 5.13%（n=5）.The magnetic molecularly imprinted polymers were prepared by suspension polymerization using nanoparticles Fe₃O₄@Si O₂as magnetic carrier,difenoxuron as a template molecular,α-methacrylic acid（MAA）as functional monomer,chloroform as orifice agent,poly vinyl alcoho（PVA）as dispersant,The influence factors on the the adsorption perpormance and morphology features were studied,such as dispersant dosage,functional monomer varieties,chloroform dosage,polymerization temperature and oscillatory speed.The results showed that under the following conditions,1.0%PVA,10m L chloroform,polymerization temperature 60℃and 500 r/min oscillatory speed,MMIP with high binding ability to the template molecular were obtained,the average diameter of MMIP were 100～500 nm,the MMIP have good shape and porous surface as well as good dispersion.Finally,the MMIP were successfully applied to detection of phenylurea pesticide residues in foods,the average recoveries were 84.4%～97.0%,the relative standard deviations（RSD）were between 1.63%and 5.06%（n=5）.The magnetic molecularly imprinted polymers were prepared by suspension polymerization taking nanoparticles Fe₃O₄@Si O₂as magnetic carrier,and the most suitable pesticides from five categories of pesticides as a template moleculars,ethylene dimethacrylate（EDMA）as crosslinking agent,azobisisobutyronitrile（AIBN）as initiator,ch-loroform as orifice agent,.The template molecule of initia functional monomer ratio and porogen were selected by ultraviolet spectroscopy analysis,the proportion of template moleculars mixture,polymerization temperature and initiator dosage were determined through MMIP adsorption capacity tests under different conditions.The morphology,dispersion and magnetic response of magnetic molecularly imprinted polymers were characterized by transmission electron microscope（TEM）,the rmogravimetric analysis（TGA）and magnetic response test.And the MMIP were applied to extiaction of five categories of pesticide residues from the food samples,the average recoveries were81.8%～98.7%,the RSDs were less than 5.93%.This method has high recoveries and good precision,and agoal was reached that the method of simultaneous separation and detection five category pesticide residues in samples using the suitable five-template Magnetic molecularly imprinted materials by a polymerization.Achieving the simultaneous enrichment,separation and detection of five kinds of pesticide residues in the samples.