The Technical Research Of Online Enrichment And Detection Contaminants In Food By In-tube Solid-phase Microextraction Coupled With Liquid Chromatography

In recent years,food safety is one of the global problems,and food safety incidents usually happed.Although new technologies for food testing have updated constantly,there were also many factors have disturbed the accurate detection,such as,interference compounds in food samples,low content of the target analytes,and so on,Therefore,sample pretreatment became one of the most important steps in the analysis of complex samples.Developing high efficient and selective pretreatment technology has been gained increasing attention in the field of food safety inspection.In-tube solid phase microextraction(in-tube SPME)has been widely used as sample pretreatment technology because of its many advantages,such as simple to operation,high extraction efficiency,cost effective,time efficient,solvent less and has been successfully applied to the extraction of trace organic compounds in food samples.In this paper,a quick and simple method based on online in-tube SPME-HPLC method for simultaneously online extraction and detection some harmful contaminants in food was developed.1.A review about the main methods and technologies of sample pretreatment,introduces the main applications of the in-tube solid phase microextraction(in-tube SPME),and the research progresses of the in-tube SPME coupled with various analytical instruments.Then the topic and research content of this work about the simultaneously online extraction and detection of some harmful substances in food with the method based on online in-tube SPME-HPLC method was proposed.2.A quick and simple method for online analysis with pre-separation,purification,and enrichment of trans-fatty acids in coffee samples has been developed.A poly(octadecyl methacrylate-co-ethylene dimethacrylate)[poly(OMA-co-EDMA)]monolithic capillary column was prepared and characterized for in-tube solid-phase microextraction(in-tube SPME),and then coupled with high performance liquid chromatography(HPLC)to realize the in-tube SPME-HPLC online analyse.In this work,4 kinds of fatty acids methyl ester(FAMEs)derivatives(9c,12c-18C:2,9t,12t-18C:2,9c-18C:l,and 9t-18C:1)were studied as the analytes.Various operation parameters,such as ACN content in the load solution,extraction flow rate,desorption flow rate and desorption time had been optimized carefully.Under the optimized conditions,the enrichment factors for four analytes were ranged from 58.3 to 70.9.The wide linear range(0.01?1.0 ?g/g)and low detection limits(LODs)(3.0~7.1?g/kg)were achieved,respectively.The present method was applied to the analysis of trans fatty acids(TFAs)in coffee,and the recoveries of the method were in the range from 83.0 to 106.4%with relative standard deviations of 3.2~4.7%(n=4)at spiking levels of 50,250 and 500 ?g/kg,respectively.The feasibility of the proposed method was demonstrated for enrichment and detection of the TFAs((linolelaidic acidin,trans-9-oleic acid)in coffee samples,which indicated that the proposed method is suitable for detecting of the two kinds of TFAs in complex samples.3.Comparing the enrichment effect of the chlorinated phenoxy acid herbicides(CPHs)(2,4-dichlorophenoxyacetic acid(2,4-D),2-(2-chloro)-phenoxy propionic acid(2,2-CPPA),2-(3-chloro)-phenoxy propionic acid(2,3-CPPA),and 2-(2,4-dichlorophenoxy)propionic acid(2,4-DP))by(poly(OMA-co-EDMA)and poly(octadecyl methacrylate-co-trimethylolpropane trimethacrylate)[poly(OMA-co-TRIM)]monolithic column)was done.Compared with the crosslinbers of EDMA and TRIM,a high hydrophobic monolithic column poly[OMA-co-TRIM]monolithic column was specially fabricated as solid-phase microextraction(in-tube SPME)column for extracting trace CPHs.Mechanical stability,monolith morphology,porosity and specific surface area properties of the poly(OMA-co-TRIM)monolith column were investigated.A rapid determination method for trace CPHs in agriculture products by in-tube SPME coupled with high performance liquid chromatography(HPLC)(in-tube SPME-HPLC)was developed.The experimental conditions of the method,such as sample volume,ACN content in the load solution,extraction flow rate,desorption flow rate and desorption time were optimized in detail.The online analysis method provides good linearity(R2>0.99)and low detection limits(0.9?2.1 ng/g).The sensitivity of the proposed method could reach that of the standard LC-MS method.Furthermore,successfully applied to the analysis of CPHs in rice grains,and the recoveries were 87.3?111.6%,with relative standard deviations of 0.6?7.3%.4.A method for trace mycotoxins(aflatoxin B1,zearalenone,sterigmatocystin)in agriculture products by in-tube solid phase microextraction(in-tube SPME)coupled with high performance liquid chromatography(HPLC)(in-tube SPME-HPLC)was developed.In this experiment,a(methylpropenoic acid-co-diethenyl-benzene)[poly(MAA-co-DVB)]monolithic column was fabricated as in-tube SPME for extracting trace mycotoxins from rice grains.Different compositions for the polymerization solution for the column were investigated,an investigation of the porosity,permeability of the best composition of the column were also involved.Extraction conditions,such as sample volume,ACN content in the load solution,extraction flow rate,desorption flow rate and desorption time were optimized systematically.Finally,under the optimal conditions,the enrichment factors for the mycotoxins were 71.9,80.0 and 98.7,respectively.Recoveries of the mycotoxins in rice grain at three spiked concentration levels varied in the range of 78.0-102.8%,with low relative standard deviations(n=4)ranged from 3.0-4.7%.Good linearity was obtained with excellent correlation coefficients(R2)being larger than 0.99,and the limits of detection were between 0.69 and 2.03 ?g/kg.The successful application of the proposed method in rice grains indicated that it is a promising approach for the determination of trace mycotoxins in complex grain samples.