Preparation And Charaeterization Of Pyraclostrobin Molecularly Imprinted Microspheres

Molecularly imprinted polymers(MIPs) is a sorbent that holds specific selectivity for target molecules and has been wildly used for preconcentration in complex matrices, based on its molecular recognition properties. Pyraclostrobin is a novel strobilurin fungicide containing pyrazole structure which is low toxicity and broad-spectrum. Due to the extensive use of pyraclostrobin, they cause a certain degree of pollution on the environment and endanger human health. The paper mainly include the following parts:The objective of this paper is to prepare molecularly imprinted microspheres which have a specific adsorption to pyraclostrobin. The present molecular imprinted microspheres are expected to be used in pyraclostrobin residues of preconcentration.At first, monodisperse micrometer-sized imprinted microspheres were prepared via precipitation polymerization using pyraclostrobine as template, MAA as functional monomer, EDMA as cross-linker and AIBN as initiator in a mixture of butanone and heptane(7:3,v:v). The adsorption experiment showed that MIP7 had the highest binding capacity when the ratio of the monomer to template was 1:6.Second, the polymers prepared in in a mixture of butanone and heptane(7:3,v:v) were characterized by zetasizer, scanning electron microscopy, nitrogen sorption porosimetry and infrared spectrometry. The microspheres showed satisfied particle size and morphology, suiting as the filler of solid-phase extraction.Third, the adsorption performance of MIP7 and NIP7 were further studied. At the concentration of 20-300mg/L, the equilibrium binding experiment showed that the binding capacity of MIP7 was higher than NIP7 obviously. Scatchard analysis indicated the Kd and Qmax of MIP7 are found to be 13.4mol/L and 15.8mg/g, the Kd and Qmax of NIP7 are found to be 84.8 mol/L and 13.3mg/g. Kinetic adsorption experiment indicated equilibrium was reached within 20 min. Selectivity analysis indicated that MIP7 had higher recognition for pyraclostrobin with the imprinted factor of 1.6. The selectivity for the other three strobilurin fungicides are kresoxim> enestroburin> azoxystrobin.