Preparation And Application Of Magnetic Adsorbent ?-cyclodextrin/Fe₃O₄@C Microsphere

In recent years,the food supervision has been paid more and more attention domestic and overseas because of food safety problems related to food pigment occurring frequently.It is imperative to develop a new type of solid phase worked with the samples and detect the pigment in food with analytical instruments because the analytical problem are low content of pigment and large the matrix in the actual sample.In this paper a new type adsorbent was prepared using magnetic Fe3O4 as the carrier,functional?-cyclodextrin??-CD?as surface modifier,which has strong adsorption ability and high selectivity for pigment,good stability,magnetic induction and reusability.And then the method of magnetic dispersive solid-phase extraction combined with high performance liquid chromatography was developed for the enrichment and separation of pigment in food analysis.The main research contents are as follows.?-CD/Fe₃O₄@C microsphere was prepared using FeCl₃·6H₂O as the iron source,glucose was the carbon source,and the?-aminopropyl triethoxysilane?KH-550?and the sulfonbutyl-?-CD as the surface modifiers.The synthetic conditions was optimized and the structure and the properties were characterized and studied by FT-IR,SEM,TEM,VSM,TG and a series of adsorption experiment.The results showed that the maximal adsorption capacity of?-CD/Fe₃O₄@C to the target analyte pigment was in range from 42.4 to 66.4 mg/g at the optimal reaction conditions,which were 5 mL of silane coupling agent?KH-550?and1.5 g of sulfonated butyl-?-CD.At the same condition,the prepared magnetic carbon composite microsphere was narrower particle size distribution,homodisperse and uniform grafted surface with?-CD derivatives,which effectively improved the surface performance of adsorption.And the results of the adsorption thermodynamics and dynamics showed that the adsorption behavior of?-CD/Fe₃O₄@C for amaranth,sunset yellow,tartrazine and new red was in according with the Langmuir equation,but for allura red adsorption model according with the Freundlich equation;the adsorption equilibrium time was 1.50 min conforming to the secondary reaction dynamics.The method of determination of synthetic pigment in food was established and the extraction conditions were optimized.The optimal condition was that the pH of the sample solution was 6.0,the dosage of the adsorbent was 100 mg,and the elution solvent was 2.0mL ammonia water-ethanol?5:95,V/V?.The recovery rate of the three food sample methods was in range from 83.06 to 102.97%,RSD was less than 6.99%.And the method detection limit was in range from 0.37 to 0.42 mg/kg.The residue concentration of 5 kinds of pigment in actual food samples was 5.60-89.6 mg/kg,which satisfied the confirmation of residual pigment in food samples and the requirement of multi-residue analysis.