Study On Preparation Of Magnetic Nanomaterial Used To Enrich Mycotoxins Of Edible Oil And It's Analytical Method

Vegetable oil is extracted from vegetables,fruits,seeds and other agricultural products by mechanical pressing or organic solvent extraction.It plays a very important role in our daily life.At present,soybeans,rapeseed,sunflower seeds,peanuts,olives and so on,are the main raw materials of edible oil production in the world.In the process of growth,these agricultural products are really easy to be polluted by mycotoxins because of the change of environment and temperature.Agricultural products contaminated with mycotoxins will eventually have seriously adverse effects on human health.In recent years,aflatoxin,deoxynivalenol,zearalenone,ochratoxin a and other mycotoxins have become more and more high in vegetable oils.Therefore,in order to protect the health of consumers,It is necessary to identify and monitor mycotoxins in different vegetable oils.The analysis of mycotoxins is challenging because they are usually low in concentration and complex in matrix.At present there is a lack of a rapid method to detect low-content mycotoxins in a variety of edible oils.The purpose of this study is to establish a simple,rapid and sensitive method for the determination of trace aflatoxin and vomiting toxin in edible oil by magnetic solid phase adsorption and fluorescence fast detection.The research contents of this paper are as follows:(1)First,magnetic nanophase materials Fe₃O₄ were prepared,then polydopamine was used to modify magnetic nanophase materials Fe₃O₄and finally,the magnetic nanophase materials Fe₃O₄ coated with polydopamines was prepared(Fe₃O₄@PDA NPs).The Fe₃O₄@PDA NPs was characterized by scanning electronmicroscopy(SEM),transmission electron microscopy(TEM),infrared spectroscopy(FT-IR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),vibrating magnetometer(VSM)et al.It was found that the prepared Fe₃O₄@PDA NPs has high affinity to aflatoxin and vomiting toxin,and it is a simple and effective magnetic solid adsorbent particle.These mycotoxins can be extracted from large volume liquid samples,and the enrichment effect is very good.The enrichment factors were 84 and89,respectively.A simple,rapid and sensitive method for the detection of low-content mycotoxins in edible oil can be developed by means of fluorescence immunoquantitative rapid detection and analysis instrument.The optimum experimental conditions were determined at the same time by a series experimentation.When the concentration and enrichment of aflatoxin were detected,the optimum experimental conditions were as follows:the ratio of Fe₃O₄ to PDA was 1:3,the amount of Fe₃O₄@PDA NPs was 0.03 g,and the volume of sample was 25 mL.When the concentration and enrichment of vomiting toxin were detected,the optimum experimental conditions were as follows:the ratio of Fe₃O₄ to PDA was 1:2,the amount of Fe₃O₄@PDA NPs was 0.02 or 0.03 g,and the volume of sample was 40mL.This method has good intra-day precision and day precision,and the RSDs are2.39%?2.48%and 1.56%?2.57%,respectively,and the recovery rate is 98.17%?101.67%.(2)On the basis of preparation of Fe₃O₄@PDA NPs,carbon diimine was used to modify Fe₃O₄@PDA NPs,and finally the magnetic nanophase materials Fe₃O₄ coated with polydopamines and carbon diimine was prepared(Fe₃O₄@PDA@EDC NPs).The Fe₃O₄@PDA@EDC NPs was characterized by transmission electron microscopy(TEM),infrared spectroscopy(FT-IR),vibrating magnetometer(VSM)et al.And the enrichment experiments of aflatoxin and vomiting toxin in edible oil were carried out.The results showed that the enrichment stability of Fe₃O₄@PDA coated with carbon diimide was greatly improved,and the recovery rate of 10 times was more than 80%,but the magnetic strength of the material was decreased,and the ability of adsorbing mycotoxin was not as good as that of Fe₃O₄@PDA,.The enrichment factor of vomiting toxin was 83,while that of aflatoxin was 75.5%.The results showed that the enrichment stability of Fe₃O₄@PDA coated with carbon diimide was improved greatly,and the recovery rate of 10 times was more than 80%,but it reduces the magnetic strength of the material.Its ability to adsorb mycotoxins was less than that of Fe₃O₄@PDA NPs,the enrichment factor of vomit toxins was 83,while of aflatoxin was only 75.5%.(3)The core-shell composite nanoparticles of Fe₃O₄@SiO₂were prepared by coating with nano-SiO₂on the surface of synthesized Fe₃O₄ magnetic nanoparticles.Then ethylene dimercaptoacetate was grafted onto the surface of Fe₃O₄@SiO₂ nanoparticles to prepare mercapto-functionalized Fe₃O₄@SiO₂nanomaterials(Fe₃O₄@SiO₂-RSH).It was characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),infrared spectroscopy(FT-IR),X-ray diffraction(XRD),vibratory magnetometer(VSM)and so on.The adsorption properties of Fe₃O₄@SiO₂-RSH nanomaterials on aflatoxin and vomiting toxin were studied by fluorescence quantitative rapid detection.The results of kinetic study showed that the adsorption of aflatoxin and vomiting toxin on Fe₃O₄@SiO₂-RSH nanoparticles materials was more consistent with the quasi-second order kinetic model,and the adsorption was mainly controlled by external diffusion.When the adsorption reached equilibrium,the enrichment factor EF of aflatoxin and vomiting toxin was 94 and 91,respectively.