| Hazard factors generally refer to substances that can affect human health.These factors can lead to tissue damage and have destructive or even lethal effects on body functions.Over the years,food safety incidents caused by food chemical hazard factors frequently occurred,such as "Poisonous milk powder","Lean meat essence","Poisonous baby bottles","Liquor plasticizer incident","Teflon incident" and so on.In order to ensure food safety,countries in the world have formulated relevant regulations and standards,and hazard factors detection technology has also been developed rapidly.Because there may be contaminants such as pigments,organic acids,sugars and fats in food,it is very important to develop new adsorbents with high selectivity and large adsorption capacity,and to establish a simple and rapid sample pretreatment technology,which could eliminate matrix interference,concentrate analytes,and improve the sensitivity of the detection method.Electrospun nano fiber is a potential adsorbent,with the advantages of high surface activity,strong permeability,fast adsorption and desorption,and easy modification.The extraction based nanofibers is simple,fast,and environmentally friendly with less dosage of organic reagent.This research aimed to solve the problems of traditional pretreatment methods,such as large amount of organic solvent,long time-consuming and low efficiency.The pesticides and veterinary drugs frequently exceeding the standard in food,or chemical hazard factors causing major food safety incidents were taken as research objects.Polystyrene-based functional nano fibers with potential interaction sites for the targets were prepared and characterized.Then,the methods for the extraction of 72 hazard factors including glucocorticoids,glucocorticoids,organophosphorus,perfluorinated compounds(PFCs)and bisphenols using were established,and the detection was used by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).The methods developed were applied to the determination of real samples.The main works are as follows:1.The extraction of 25 glucocorticoids in milk using polystyrene nano fibersBy association analysis of the characterization parameters and extraction effect of the nano fibers,and in comparison with the conmmercial micronparticle type copolymer adsorbents,it is clear that the morphology was one of the key factors to improve the adsorption efficiency of materials.The matrix effect of the method for 25 glucocorticoids was-5.6%-4.2%.The method validation data showed a great linearity in the range of 1-100 μg/L,with the correlation coefficients higher than 0.995.The limits of detection and quantification were 0.04-0.10 μg/kg and 0.13-0.33 μg/kg.The recoveries were 71.5%-105.1%,with the relative standard deviation(RSD)of 1.8%-10.1%.This method had been applied to the detection of glucocorticoids in milk,and traces of cortisol were detected in.a commercial sample.2.The extraction of 14 fluoroquinolones in animal food using sulfonated polystyrenepolyvinylpyrrolidone nanofibersCompared with polystyrene,the hydrophilicity of the sulfonated polystyrenepolyvinylpyrrolidone nanofibers was increased,which was favorable for the adsorption of fluoroquinolones with high polarity.The carbonyl group of pyrrole ring,the sulfonic group distributed on the nanofibers surface,and the aromatic nucleus were potential interaction sites,which could form hydrogen bond,electrostatic interaction,and π-π interaction with the targets.The method validation data showed a great linearity in the range of 0.1-50.0 μg/L,with the correlation coefficients higher than 0.995.The limits of detection and quantification were 0.050.20 μg/kg and 0.17-0.66 μg/kg.The recoveries were 84.9%-105.8%,with the RSD of 1.0%11.5%.In the sample analysis,the results used this method were consistent with the national standard detection method,and the total amount of enrofloxacin and ciprofloxacin detected in some samples exceeded the national standard3.Application of polystyrene-polypyrrole nano fibers in migration detection of 17 PFCs)in food contact materials(FCMs)The determination of PFCs in FCMs and foods are facing a key challenge because of the low concentrations.The detection requires not only the high-sensitivity detector,but also pretreatment technology that could reduce matrix effect and enrich target compounds.In this study,the polystyrene-polypyrrole nanofibers with multiple interaction sites on the surface were used to carry out the enrichment and concentration pretreatment of PFCs in the sample solution.Because of the strong adsorption of the nanofibers to PFCs,ammonium acetate-acetic acid solution was added into methanol to improve the extraction efficiency of the targets.The method validation data showed that the linear correlation coefficients of 17 PFCs were all more than 0.997.The limits of detection and quantification were 0.6-5.0 ng/kg and 2.0-20 ng/kg.The recoveries were 89.4%-120.0%,with the RSD of 0.2%-9.8%.The method was used to detect the PFCs in FCMs such as barbecue paper and microwave popcorn bags.The positive samples were selected to carry out migration experiment to explore the migration of barbecue paper to meat products in actual use.4.Determination of bisphenol F and bisphenol S in food simulates using polystyrenepolypyrrole nanofibersThe adsorption mechanism of nanofibers to bisphenol F and bisphenol S was clarified through the comparison of different nano fibers in adsorption properties.The extraction column packed by polystyrene-polypyrrole nanofibers could well adsorb the target substances in water,4%acetic acid and 10%ethanol.The column could be reused for 10 times with the extraction efficiency of 72.8%-84.2%.The method validation data showed that the linear correlation coefficients of BPF and BPS were both greater than 0.999.The detection limits of the method were 0.1 μg/L and 0.01 μg/L,and the quantitative limits were 0.3 μg/L and 0.03 μg/L.The recoveries were 100.6%-110.9%,with the RSD of 96.2%-107.2%.During the sample analysis,a small amount of bisphenol S was detected in yogurt cups and ice cream cups5.Preparation of polystyrene-hydroxylated multi-walled carbon nanotubes-polypyrrole composite nanofibers and their application in the detection of organophosphorus pesticidesThe polystyrene-hydroxylated multi-walled carbon nanotubes-polypyrrole composite nano fibers were prepared by blending co-spinning and in-situ polymerization.The benzene ring,pyrrole ring,hydroxyl group and six-membered carbon ring of the nanofibers could provide multiple interaction sites such as hydrogen bond,hydrophobic interaction,π-π conjugation and ion exchange.The results showed that the composite nano fibers exhibited good and rapid adsorption of impurities such as pigments,organic acids and sugars,but weak adsorption to the targets in acetonitrile.The matrix removal effect of this extraction was equal with the QuECHERS(Quick,Easy,Cheap,Effective,Rugged,Safe)method.The method validation data showed a great linearity in the range of 1-200 μg/L,with the correlation coefficients higher than 0.999.The limits of detection and quantification were 0.03-0.3 μg/kg and 0.01-1.0 μg/kg.The recoveries were 65.2%-125.3%,with the RSD of 0.4%-11.6%.In this method,only one composite nanofiber was used as adsorbent to purify,while two or three materials were used in QuECHERS method.The exctracion method need low consumption of organic solvent without centrifugation.The novel method was used for the detection of organophosphorus pesticides in vegetables.In summary,through the improvement and modification of polystyrene nanofibers,combined with HPLC-MS/MS,the detection methods for 72 food chemical hazard factors were established,applied and evaluated.The extraction technology based on nanofibers has the advantages of simple operation,less time-consuming,low dosage of adsorbent and organic solvent,and environment protecting,which has wide application prospect in food detection. |
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