Sample Pretreatment Methods In Food Safety Analysis

Due to the complexity of food matrix and the low concentration of contaminants,in the process of establishing food safety analysis methods,sample preparation technology is very important,and effective extraction and purification is still a challenging work.With the continuous development of green chemistry,how to apply and reflect the characteristics of green chemistry in the analysis process,and avoid the secondary pollution of the analysis process and the possible harm to the analysts have also received extensive attention.In recent years,significant progress has been made in the development of green solvents.Therefore,the development and use of solvents with green chemistry characteristics is the one of the main work for analysts.In addition,the synthesis and use of various new materials and new methods have also been favored.Among the new solvents,magnetic ionic liquids?MILs?,deep eutectic solvents?DES?,and Qu ECh ERS methods have stood out due to their green chemistry characteristics,excellent enrichment and separation performance.In this dissertation,endogenous interfering substances?bisphenol A and nonylphenol?,synthetic pigments,illegally added dyes,and pesticides in food samples were analysized.Based on the Qu ECh ERS method and magnetic ionic liquids,deep eutectic solvents with “green chemistry” characteristics,we established a rapid analysis method for the above-mentioned substances in various foods.Our works are mainly as follows:1.A novel method was developed for the determination of two endocrine disrupting chemicals,bisphenol A and 4-nonylphenol,in vegetable oil by dispersive liquid-liquid microextraction followed by ultra-high performance liquid chromatography-tandem mass spectrometry?UHPLC-MS/MS?.Using magnetic ionic liquid as the microextraction solvent,several key parameters were optimized,including the type and volume of the magnetic liquid,extraction time,amount of dispersant and the type of reverse extractant.The detection limits for bisphenol A and 4-nonylphenol were 0.1 and 0.06 ?g/kg,The recoveries were 70.4%-112.3% and the relative standard deviations were less than 4.2%.The method is simple for extraction of bisphenol A and 4-nonylphenol from vegetable oil,and suitable for routine analysis.2.It was developed an ultrasonic-assisted extraction method with choline chloride/hydrogen bond donor?Ch Cl/HBD?DES for the extraction of chrysoidine G?COG?,astrazon orange G?AOG?,and astrazon orange R?AOR?in food samples.Some experimental parameters,such as extraction time,raw material/solvent ratio,and temperature,were evaluated and optimized as follows: the ratio of Ch Cl/HBD,1:2?v/v?;the ratio of sample/DES,1:10?g/m L?;extraction time,20 min;extraction temperature,50°C.Under the optimized conditions,the limits of detection?g/m L?were 0.10 for COG and 0.06 for AOG and AOR.The relative standard deviations were in the range of 1.2-2.1%.The recoveries of the three dyes were in the range of 80.2-105.0%.By comparing with other commonly used solvents for extracting chrysoidine dyes,the advantages of DESs proved them to be potential extraction solvents for COG,AOG,and AOR in foods.3.Common DES are water-soluble and they are limited to applied in some samples analysis.A method was developed for the determination of eight synthetic pigments in beverage samples using hydrophobic DES as the microextraction solvent,followed by HPLC.Several key parameters were optimized,including the type and volume of the hydrophobic DES,p H value,vortex time and salt content.Detection limits were in the range 0.016-1.12 ng/m L,recoveries were in the range 74.5-102.5% and relative standard deviations were<5.4%.4.A magnetic DES was synthesized.The liquid malonite green crystal violet and its metabolites leucomalachite green and leucocrystal violet were evaluated by liquid-liquid microextraction method.We studied and optimized the main extraction factors,such as the amount of MDES,vortex extraction time,and established a method for the determination of malachite green,crystal violet and its metabolites by liquid-liquid microextraction combined with ultra-high performance liquid chromatography tandem mass spectrometry.The detection limit of the four dyes was in the range of 0.06-0.52 ng/m L,the recovery was 89.2-102.4%,and the relative standard deviation was <4.2%.5.Based on the rapid development and powerful application potential of the Qu ECh ERS method with green chemistry characteristics,we synthesized a magnetic material to replace C₁₈ in the Qu ECh ERS method,to improve the Qu ECh ERS method.It was applied to the extraction and purification of pesticide residues in tea beverages.We established a HPLC-MS method for the analysis of 8 pesticide residues in different food matrices.In the process of different matrix samples,the recovery rate similar to that of C₁₈ is obtained,the method is simple and feasible,and the magnetic material can be reused after being washed by methanol,which saves the cost of the method.