Determination Of Pesticide Residues In Soybean Oil By Liquid Chromatography Tandem Mass Spectrometry And Study On Processing Factors

China is a large country of oil production and consumption,and soybean oil plays an important role in our national oil intake.In order to ensure crop yield,the use of pesticides is inevitable in the process of agricultural production,but the use of pesticides will lead to food safety problems.In the process of oil processing,pesticide residues will be transferred from oilseeds to vegetable oil.In the process of soybean pressing,different processing steps will lead to changes in the level of pesticide residues in soybean oil.However,at present,the change behavior of pesticide residues in soybean oil processing is not clear.Therefore,it is necessary to study the pesticide residue behavior and processing factors in the key processing steps of soybean oil production.However,at present,there are many kinds of detection methods for the analysis of pesticide residues in soybean oil,the types of pesticides are relatively scattered,and there are few methods to detect a variety of pesticide residues in soybean oil at the same time.Therefore,this study developed a method to detect many kinds of pesticides in soybean and soybean oil to provide technical support for food safety monitoring.Then the changes of pesticide residues in soybean processing were studied,and the experimental data such as processing factors were improved,in order to provide optimization data for soybean processing technology.The optimized Qu ECh ERS method combined with UHPLC-MS/MS was used for detection.The results showed that acetonitrile solution containing 1%formic acid was selected as the extraction solvent,the adsorbent of soybean sample was 50 mg C18,and the adsorbent of soybean oil sample was 50 mg C18 and 50 mg PSA.Acetonitrile containing 0.1%formic acid aqueous solution was selected as the mobile phase.The flow rate of the mobile phase was 0.3 m L/min,which had good response value and peak shape.Under the optimized conditions,the calibration curves of all pesticides were linear in the concentration range of 10-1000μg/L,and the correlation coefficient(R~2)was greater than 0.9945.Recovery range:70.1-120.0%,relative standard deviation(RSD,n=5)≤20.0%.The limits of detection(LOD)range:0.5-10μg/kg,the limits of quantitation(LOQ)range:2.0-30μg/kg,and the matrix effect(ME)range:-18.77-19.33%.This method has been successfully applied to the qualitative and quantitative analysis of pesticide residues in vegetable oil samples from Chinese supermarkets.It has been proved that the method is accurate,linear,sensitive and stable,and can simultaneously detect a variety of pesticides in oil crop products.By using the established multi-pesticide residue analysis technique,13 pesticides commonly used in soybean planting in China were selected to study the residue behavior of the key processing steps in soybean crushing process,and the processing factors were calculated.The results showed that the processing factors of Imidacloprid and Bentazone in soybean oil were less than 1,and the processing factors of Clomazone were less than 1 after being pressed at 170℃.The processing factor of cold pressed soybean oil was generally higher than that of hot pressed soybean oil except for Bentazone.The processing factors of other pesticide residues were greater than 1.Further study on pesticide behavior of pesticide residue in the physical and chemical properties of soybean products,the effect of the processing factors of pesticide residue from its physical and chemical properties parameters(octanol-water partition coefficient(Log Kow),water soluble(Sw),melting point(Mp),vapour pressure(Vp)to carry on the non-linear curve fitting,the result shows that processing factor and the Log is closely relative to the Log Kow,Vp,It was negatively correlated with Sw and Mp.In this study,a new method for the determination of 38 pesticides in soybean and soybean oil complex matrix was developed,and the pesticide residue behavior and processing factors in soybean oil processing were studied,so as to provide theoretical basis and technical support for the formulation of maximum residue limit(MRL)standard of soybean products and food safety risk assessment.