Study On Zr⁴⁺-based Magnetic Metal Organic Framework For Solid Phase Extraction Of Insecticides And Herbicides In Foodstuffs

Objectives Sample preparation is an important part of pesticide detection in food matrix.Due to the complexity of matrix in food samples,an effective pre-treatment process is required to enrich the target analytes and minimize matrix interferences before instrumental analysis.To overcome the shortcomings of traditional pre-treatment technology,such as tedious operation and high cost,a novel and reusable magnetic metal organic framework composite was synthesized and applied as an adsorbent for the magnetic solid phase extraction?MSPE?combined with high performance liquid chromatography-ultraviolet?HPLC-UV?analysis for determination of insecticides in drinks?tea beverages and juice?and herbicides in rice samples.Methods 1 A novel magnetic metal organic framework composite?Fe₃O₄@MOF-808?was synthesized by a facile solvothermal method.The prepared material was characterized by Fourier-transform infrared spectroscopy,X-ray diffractometry,scanning electron microscopy,vibrating sample magnetometry measurement and specific surface and aperture analyzer for its groups,morphology,magnetic strength and specific surface area.2 The prepared Fe₃O₄@MOF-808 was applied for an effective adsorbent for the MSPE of seven benzoylurea insecticides?BUs?from tea beverages and juice samples.The adsorption parameters?adsorbent amount,extraction time,p H and Na Cl concentration?and elution parameters?elution solvent,elution volume and time?were investigated in detail.Under the optimal conditions,the adsorption mechanism of the adsorbent was studied,and the method was validated with linearity,limit of detection?LOD?,limit of quantification?LOQ?,accuracy and precision.In addition,the reusability of the Fe₃O₄@MOF-808 was also assessed by calculating the relative standard deviation?RSD?of the peak area of the BUs while performing consecutive adsorption-desorption cycles.Finally,the prepared adsorbent was compared with a commercial C₁₈ adsorbent in the term of adsorption property.3 Fe₃O₄@MOF-808 was further used as an adsorbent for MSPE of three diphenyl ether herbicides?Des?in rice samples.The parameters including adsorbent amount,extraction time,elution solvent and elution volume were investigated in detail.Method validation was evaluated by linear range,LOD,LOQ,accuracy and precision.Results 1 The characterization results showed that the spherical Fe₃O₄ particles were uniformly attached to the surface of the octahedral MOF-808 crystals.The maximum saturation magnetization and specific surface area of this composite material were found to be 40.35 emu.g^-1 and 117.88 m².g^-1,respectively.2 A new method based on MSPE using Fe₃O₄@MOF-808 combined with HPLC-UV had been developed and applied to analyze BUs in tea beverages and juice samples.60 mg of the Fe₃O₄@MOF-808 was used and the extraction was simultaneously performed while stirring for 15 min.The preconcentrated target analytes were then eluted with 2 m L of acetonitrile by stirring for 3min.And there was no need to adjust the p H and Na Cl concentration of the sample solution.The method provided low LODs(0.04-0.15 ng.m L^-1),wide linear ranges(0.15-50 ng.m L^-1)with all correlation coefficients?r?exceeding 0.997 and satisfactory enrichment factors(104^-116).The recoveries for three replicate extractions of BUs were from 84.6% to 98.3% with RSDs between 2.6% and 11.4%.The RSDs for all targets in tea beverages were less than 10.2% in 10 successive cycles of extraction/desorption of Fe₃O₄@MOF-808.Notably,?-? interactions,hydrophobic interactions and hydrogen bonding interactions contributed to the good adsorption of BUs by Fe₃O₄@MOF-808.The Fe₃O₄@MOF-808 exhibited equivalent extraction effect with commercial C₁₈.3Based on Fe₃O₄@MOF-808,MSPE combined with HPLC-UV was developed to determine three Des in rice samples.As 1 g of sample was taken,the Des could be adsorbed absolutely by using 25 mg of Fe₃O₄@MOF-808 with no more than 6 min.A total of 0.5 m L×2 of methanol was selected as the elution solvent.The method showed good linear relationships in the range of 1^-150 ?g.kg^-1 with correlation coefficients higher than 0.998.The detection limits were 0.4-0.6 ?g.kg^-1 for all the analytes.The recoveries at three spiked levels of Des ranged from 87.3% to 96.7%.Intra-day and inter-day precisions were 2.9%-8.2% and 4.2%^-10.8%,respectively.Conclusions 1 The Fe₃O₄@MOF-808 was developed as adsorbent for MSPE combined with HPLC-UV for determination of seven BUs in drinks?tea beverages and juice?and three Des in rice.2 The proposed method was simple and rapid,and could meet the requirements of the analysis for pesticide residues in food matrix.Notably,the adsorbent was easy to be prepared and cost-saving since it could be reused at least 10 times.Figure 15;Table 9;Reference 149...