Synthesis Of Three Magnetic Adsorbents And Their Application In Residue Analysis Of Triazole Fungicides

Triazole fungicides have been widely used for the prevention and treatment of many diseases due to their high efficiency,low toxicity,good systemic properties and other characteristics.The residual pesticide will bring potential harm to human.In this paper,three kinds of magnetic adsorption materials based on metal-organic framework（MOF）were designed and synthesized,and they were used as adsorbents in the process of magnetic solid-phase extraction.Finally,the residue analysis methods of three triazole fungicides were established by combining with high performance liquid chromatography（HPLC）.The details are as follows:1.Preparation and application of Fe₃O₄@TYUT-96Cr:In order to verify the successful synthesis of magnetic composite Fe₃O₄@TYUT-96Cr,a series of characterization and analysis were carried out.Characteristic functional groups,morphology and crystal structure can be observed by characterization,and magnetic separation can be carried out quickly.Subsequently,this material was applied to the magnetic solid phase extraction process.In order to obtain the best extraction effect,the single variable method was used to optimize the parameters.The optimum conditions were as follows:the dosage of adsorbent 40 mg,extraction time 9 min,p H 7.0,elution solvent and volume of acetonitrile 1.0 m L,and the ionic strength of the system was not changed.It was verified by the method that the three triazole fungicides showed good linearity in the range of 10μg/L-1000μg/L,with R²≥0.9958 and The LOD value between 0.030μg/m L and 0.167μg/m L.The above results prove that this method meets the requirements of pesticide residue analysis.Finally,the established method was applied to six kinds of fresh juice samples.Results It can be observed that no target fungicide residue was detected in the fresh squeezed juice.The recovery rate of three triazole fungicides in the spiked samples was 64.3%-109.7%,and the RSD was≤10.1%.It shows that this method has good application potential.2.Preparation and application of Fe₃O₄@PPy@MIL-53（Fe）:In order to verify the successful synthesis of magnetic composite Fe₃O₄@PPy@MIL-53（Fe）,a series of characterization were carried out.Characteristic functional groups,morphology and crystal structure can be observed by characterization,and magnetic separation can be carried out quickly.This material was applied to MSPE process.In order to obtain the best extraction effect,the single variable method was used to optimize the conditions.The obtained conditions were as follows:the dosage of adsorbent was 30 mg,the adsorption time was 20 min,the extraction time was 5 min,the p H was 6.0,and the elution solvent was acetonitrile.In order to evaluate the accuracy,linear range and other parameters of the established method,the method was verified under the best conditions.The results showed that the three triazole fungicides showed good linearity in the range of10μg/L-1000μg/L,with R²≥0.9994 and The LOD values ranging from 0.025μg/m L to0.038μg/m L.These results prove that the method meets the requirements of pesticide residue analysis.Finally,the established method was applied to three kinds of fresh juice samples and two kinds of environmental water samples.Results No target pesticide was detected in all the tested samples,and the recovery rate of target pesticide in the spiked samples was 78.6%-105.4%,with RSD≤5.7%.It shows that this method can be applied to the residue analysis of triazole fungicides.3.Preparation and application of Fe₃O₄@Zn Al-LDH@MIL-53（Al）:In order to verify the successful synthesis of magnetic composite Fe₃O₄@Zn Al-LDH@MIL-53（Al）,a series of characterization were carried out.Characteristic functional groups,morphology and crystal structure can be observed by characterization,and magnetic separation can be carried out quickly.The magnetic composite was applied to MSPE process.In order to optimize the adsorption and extraction effects,all the conditions were optimized,and the best conditions were obtained as follows:the dosage of adsorbent30 mg,adsorption time 15 min,extraction time 5 min,p H6.0,elution solvent acetonitrile and ionic strength 4%.In order to evaluate the accuracy,linear range and other parameters of the established method,the method was verified under the best conditions.The results showed that the three triazole fungicides showed good linearity in the range of 10μg/L-1000μg/L,with R²≥0.9796.The LOD value is between 0.013μg/m L and 0.030μg/m L.These results prove the feasibility of this method,and it can be further applied in practical samples.Finally,the established method was applied to four kinds of juice samples,and the results showed that no target pesticide residues were detected in all the fresh squeezed juices.The recovery rate of the spiked samples was between 73.3%and 104.3%,and the RSD was≤5.5%.It shows that this method can be applied to the residue analysis of triazole fungicides.