Application Of Metal-organic Frameworks Functionalized Magnetic Composite For Magnetic Solid-phase Extraction Of Organic Pesticide Residues

Organic pesticides were usually applied to the modern agriculture,such as herbicide and insecticide.However,being chemically stable and hard to degradation,they can accumulate and their residues have been found to be environmental contaminants and harmful to human health.It is therefore necessary to develop a sensitive,rapid,and accurate method for determining organic pesticides at trace levels.Metal-organic frameworks(MOFs)have unusual properties and fascinating structures,and have been used in pretreatment techniques to adsorb and separate species of interest from samples.In this work,the magnetic properties of Fe3O4 nanoparticles and the adsorption characteristics of MOFs led us to synthesize magnetic MOFs composites,and the composites were used to extract pesticide residues prior to analysis with high-performance liquid chromatography(HPLC).The results demonstrating that magnetic MOFs composites show great promise for the extraction of pesticide residues from complex 'samples.The properties of polydopamine(PDA)modified Fe3O4 nanoparticles and the adsorption characteristics of MIL-53(Fe)led us to develop a simple one-pot solvothermal for synthesizing MIL-53(Fe)@PDA@Fe3O4 composites.The composites were introduced to extract four kinds of sulfonylurea herbicides,and then analyzed by HPLC system.Significant extraction parameters and chromatographic conditions were discussed,and the developed method showed good linearities with correlation coefficients no less than 0.9980.The limits of detection were 0.28-0.77 ?g/L,and relative standard deviation lower than 7.8%(n = 6).The method was successfully used to determine sulfonylurea herbicides in the environmental water samples with satisfactory recoveries ranging from 78.8%to 109.7%.Therefore,the method is a simple,rapid,and cost-effective extraction procedure for the analysis of sulfonylurea herbicides.Magnetic MIL-101(Fe)@PDA@Fe304 composites which combined the advantages of Fe304 with high adsorption capabilities of MIL-101(Fe)were prepared,and used as magnetic adsorbent to rapidly extract sulfonylurea herbicides prior to analysis with HPLC.Good linearity was found(correlation coefficients>0.9991)using the optimal conditions.The limits of detection were low,at 0.12-0.34 ?g/L,and the relative standard deviations lower than 4.8%(n = 6).The method was successfully used to determine four sulfonylurea herbicides in environmental water and vegetable samples,giving satisfactory recoveries of 87.1%-108.9%.The extraction efficiency was compared with other magnetic composites,the results showed that the magnetic MIL-101(Fe)@PDA@Fe3O4 composites have great potential for the extraction of trace sulfonylurea herbicides from various sample types.Poly(acrylic acid)(PAA)modified Fe3O4 nanoparticles,and then magnetic IRMOF-3@Fe3O4/PAA composites were synthesized via encapsulation method.The composites used as adsorbent for extraction of the four pyrethroid insecticides prior to HPLC analysis.The main experimental parameters were optimized,and the developed method showed good linearity with correlation coefficients higher than 0.9989.A low limit of detection varied from 0.18 ?g/L to 0.44 ?g/L and good repeatability(relative standard deviation lower than 6.1%,n = 6)were obtained.The method was successfully used to determine pyrethroid.insecticides in tea beverage and tea samples with recovery ranging from 81.3%.to 105.3%.The results demonstrating that magnetic IRMOF-3@Fe3O4/PAA composites show great promise for the extraction of pyrethroid insecticides.