Development Of Magnetic Dispersive Solid Phase Extraction Of Phenolic Compounds Based On Magnetic Nanoparticles And Deep Eutectic Supramolecular Solvent

Due to the complexity of the sample matrix,sample pre-treatment is considered an indispensable step in the overall analytical operation.Sample pre-treatment methods should be simple,rapid and economical,and with good sample purification and extraction recovery that improve the detectability of the analytical technique for the sample.Magnetic dispersive solid phase extraction（MSPE）is of interest to many researchers due to its special features of the extraction process.Magnetic nanoparticles（MNPs）capturing the target analytes can be easily collected using an external magnetic field without the need for centrifugation and filtration processes,thus reducing the analysis time and simplifying the separation process.In MSEP,a sorbent sensitive to the target compound and an efficient desorbing solvent are key to the extraction technique.In this paper,functionalised nanoparticles have been synthesised as sorbents and deep eutectic solvents and（DES）deep eutectic supramolecular solvents（DESP）have been used as desorbents to achieve excellent extraction results.The specific studies in this paper are as follows.（1）Magnetic chitosan nanoparticles（CS@Fe₃O₄MNPs）,magneticκ-carrageenan nanoparticles（KC@Fe₃O₄MNPs）,DES and DESP were synthesized and analysed by¹HNMR,FT-IR,XRD,SEM,TEM,ESD,VSM,TG,BET and contact angle,which confirmed the successful synthesis of the materials.（2）Four phenolic compounds,gallic acid,catechin,caffeic acid and ferulic acid,contained in common foods were determined by MSPE technique.For the first time,CS@Fe₃O₄MNPs were combined with DESP in the MSPE technique.CS@Fe₃O₄MNPs were used as adsorbents with easy synthesis and recoverability.Moreover,DESP was used as a green eluent due to its excellent desorption efficiency.The technique shows good methodological and greenness.Therefore,the developed method has potential application in the analysis of phenolic compounds in food samples.（3）Three flavonoids,rutin,quercetin and kaempferol,were enriched and isolated from black tea,onion,honey,carrot,cocoa bean and black buckwheat samples using the MSPE technique.DESP was applied as a desorbent in the desorption process instead of organic solvents,reducing environmental pollution and improving desorption efficiency.The technique established by optimising the extraction conditions was well evaluated methodologically and has good antioxidant activity for the extraction and determination of flavonoids in various food matrices.（4）Magneticκ-carrageenan nanoparticles were used for the adsorption of catechol and the adsorption process was investigated in terms of kinetics,isotherm curves,thermodynamic analysis and the effects of p H and salt concentration.At the same time,the factors affecting the desorption efficiency were systematically investigated:the effects of the type of desorbent,the amount of desorbent,the mode and time of desorption and the concentration of desorbent on the extraction effect,so as to obtain the optimal experimental conditions for the extraction.Finally,the method was used to determine the content of catechol in tap water,river water,lake water and sewage.The results show that the established method can well enrich and detect trace catechol in the environment and has broad development and application prospects in future ecological environmental protection.