Studies On The Determination Of Aflatoxin And Polycyclic Aromatic Hydrocarbons In Food Using Deep Eutectic Solvent

Food is the material base for human survival and development,and its safety is related to human health.As some pollutants may be introduced into food in the production,processing,storage,transportation and other aspects,it is of great significance to strengthen the monitoring of its quality.Due to the complexity of food matrix and low concentration of contamination,sample pretreatment technology is very important in achieving effective analysis of contaminants.Traditional sample pretreatment technology is complicated,inefficient and sometimes requires a large number of organic solvents,which will cause secondary hazards to the analysts.Therefore,it is particularly important to develop new and effective food sample pretreatment technology.Deep eutectic solvent(DES)is regarded as a new green solvent.Due to its excellent physical and chemical properties,DES has been widely used in extraction and separation.In the study,combining high performance liquid chromatography with fluorescence analysis technology(HPLC-FLD),a new method for the analysis of PAHs and aflatoxins in foods was developed by using DES as green extractant,which was applied to the analysis of actual samples and obtained good results.The research results are as follows:(1)Several deep eutectic solvents were prepared with choline chloride and different hydrogen bond donors respectively.Combined with liquid phase microextraction technology,a new method for the determination of four aflatoxins in edible oils was established.It was found that DES had good extraction and enrichment effects on multi-hydroxyl structural aflatoxins G1,G2,B1 and B2,furthermore,G1 and B1 show fine fluorescence property after being extracted by DES,which could be used for stable analysis in HPLC-FLD.Therefore,DES plays a dual role of extraction and derivation in the process of liquid phase microextraction,greatly simplifies the steps of oil sample pretreatment and significantly reduces the detection cost.The extraction conditions were systematically optimized by response surface methodology(RSM).The detection limits of four aflatoxins were0.0005-0.003?g/kg.The recovery was 77.06%-112.02%and the relative standard deviation was less than 10%.These results showed that the method could meet the analysis requirements of four aflatoxins in edible oil.(2)Six DESs were successfully prepared with malonic acid and different hydrogen bond acceptors(choline chloride,tetramethylammonium chloride and betaine)at different molar ratios.Combined with HPLC-FLD,a new method for simultaneous analysis of four aflatoxins(aflatoxins G1,G2,B1 and B2)in rice was established.The effects of extraction conditions(type of extractant,extraction time,extraction temperature,volume of extractant and ratio of extractant to water)on four aflatoxins were systematically discussed.Under the optimal conditions,the linear range of the four aflatoxins was 0.03-20?g/L with good correlation coefficient(R~2>0.997),the detection limit was 0.005-0.06?g/kg,and the recoveries were in range of 78.93-113.64%.This method could achieve an effective analysis of four aflatoxins in rice.(3)Four hydrophobic deep eutectic solvents were prepared by mixing tetrabutylammonium chloride and lidocaine as hydrogen bond acceptors with n-octanol and n-octanoic acid as hydrogen bond donors,respectively.Combined with HPLC-FLD,a new method was developed for the determination of six polycyclic aromatic hydrocarbons(PAHs)in milk samples by applying the well hydrophobicity of DES into forming two non-dissolved phase between DES and milk.The effects of various extraction conditions(the type of extractant,extraction time,extraction temperature,amount of extractant and salt content)on the extraction efficiency of six PAHs in milk were systematically discussed.Under the optimal conditions,the results show that six PAHs can be extract better by DESs.The recoveries and RSDs are in the range of 70.87-100.45%and 1.05-8.95%,respectively.The detection limit of the method is between 0.03-0.3?g/kg.These result illustrated the method is fast,simple and environmentally friendly,and is suitable for the determination of PAHs in milk.