Preparation And Application Of Magnetic Solid Phase Extraction Material Based On Dopamine Modified Graphene Oxide

Nowadays,food safety has gained increasing attentions because humans are seriously endangered by numerous contaminants in food stuffs.While chromatographic instruments have made great technological progress in the past few decades,the effective food pretreatment methods are still an essential step both in qualitative and quantitative analysis of trace contaminants in complexity food matrices,which deserves serious attention.Recently,the innovation of emerging nanotechnology and nanomaterials has greatly promoted the development of food sample pretreatment methods.Inspired by mussels,we follow the concept of green synthesis and develop nanotechnology to product sustainable,economical,safe,and ecofriendly nanomaterials in this work.These materials not only have a good enrichment capacity for target pollutants,but also could reduce secondary pollution to the environment and is easy to recycle,compared with traditional nanomaterials.They showed great application prospects for the pretreatment of food samples.(1)A new restricted access material(RAM)based on graphene oxide(GO)and a temperature-response polymer brush was developed and used as an adsorbent of the magnetic solid-phaseextraction(m-SPE)for malachite green(MG).The best enrichment conditions are obtained by optimizing the main parameters that affect the extraction efficiency.The adsorption and desorption of MG could be achieved on the obtained smart material only through changing the temperature of the solution.The smart material and aqueous solution achieve separation using a magnet within 2 min.An effective analytical method for MG was developed by combining with a UV-Vis spectrophotometer.It indicated that the new method can be applied in the determination of trace or ultra-trace MG in complex real samples.(2)MGO@PDA@MoS2 nano-flower material was prepared by insitu growth of MoS2 on the poly-dopamine(PDA)modified Fe3O4@GO(MGO)nanosheets and was used as a m-SPE adsorbent.The nanocomposite was characterized by TG,VSM,SEM,TEM,XRD,XPS and FT-IR.The extraction parameters were investigated,including initial concentration,extraction time,pH,ionic strength and desorption conditions.The adsorption behaviors of the material were explored via isotherm and kinetic adsorption experiments,which demonstrated that Langmuir adsorption isotherm model and pseudo-second-order kinetic model were more appropriate to describe the adsorption process on MGO@PDA@MoS2.A rapid,safe,sensitive,easy,and effective method has been developed for detecting cyromazine and melamine at same time in real samples including beef,protein powder and milk by combined with high-performance liquid chromatography(HPLC).(3)A magnetically recyclable nano-composite of MGO@PDA@ZIF-67 based on ZIF-67 and PDA modified MGO nanosheets was synthesized and used as a m-SPE adsorbent to enrich praziquantel and pymetrozine.It reduces the hydrophobicity of MGO and improves the hydrophilicity of the MGO@PDA@ZIF-67 by using PDA as a molecular linker.Besides,using the MGO@PDA as substrate greatly overcame the disadvantages of ZIF-67 crystal powder that is easy to aggregate and difficult to recycle.The adsorption behaviors of the material were investigated by isotherm and kinetic adsorption experiment.The results show that the new m-SPE adsorbent exhibits a high adsorption capacity,good selectivity and wide pH adaptability(3-11).The maximum adsorption capacity of the new material for praziquantel and pymetrozine are 22.68mg·g-1 and 24.27mg·g-1,respectively.This work provides some inspiration for developing more advanced and reliable water-stable ZIFs for the determination of trace target analytes in complex samples.