Determination Methods For Representative POPs And Dioxin Contamination In Animal Source Foods From Typical Areas

Long-distance migration and bioaccumulation of persistent organic pollutants(POPs)cause a high risk of food contamination,which brings great risks to human health.It is of great significance to establish fast,low-cost and high-throughput analysis methods for POPs in animal source foods,and to study dioxin contamination of foods in typical regions for food safety and environmental health risk control.In this study,verified the applicability of the cell bioassay for dioxins in animal source foods.A bioassay system of recombinant cell lines based on nuclear receptor CAR was exploratory constructed.The system laid the foundation for the subsequent identification and analysis of POPs.The complex and expensive sample purification methods and materials of HRGC-HRMS used in dioxins analysis in food were improved.And the new method maintains good accuracy and sensitivity while saving time and reducing cost.The GC-MS/MS screening method for 95 POPs from animal-source foods was established,the method meet the requirements of rapid determination.The contamination level,distribution characteristics and dietary exposure risks of dioxin and DL-PCBs of animal source foods in typical area were studied.(1)For CBG2.8D bioassay,the average recovery and relative standard deviation of multilevel matrix spike were 102% and 20%,respectively,and the accuracy and precision of the method met the requirements.The correlation coefficient between TEQ results and HRGC-HRMS for PCDD/Fs and DL-PCBs was 0.88 and 0.92,respectively,after correcting for the difference between BEQ and TEQ.The actual sample verified used the CBG2.8D bioassay had no false negative results,meet the requirements of high-throughput screening methods.In the series of reporter plasmids constructed based on CAR target genes,the reporter plasmid constructed based on CYP2B6 had relatively high response to PB,and the XREM+1.8 kb PBREM plasmid induced luciferase was about 21 times to DMSO,it is high sensitivity plasmid.The reporter plasmid induced luciferase to 1m M PB was3.5 times 1.0 μM CITCO.The linear range used the CITCO of as the specific ligands of CAR was from 1 n M to 60 μM.The linear range of identification and detection of inhibitory compounds was established with PK11195 as the standard compound,and the range was from 1 n M to 60 μM.The MDL of the constructed detection system is 1 n M.The IC50 of CITCO is 0.1 μM,and the EC50 value of PK11195 is 0.7 μM.The established CAR gene recombinant cell biodetection system can be used in the construction of organic pollutant screening methods.(2)For silica gel-carbon chromatography column purification,the dichloromethane/hexane purification-toluene positive phase elution system be used.The recoveries of PCDD/Fs and DL-PCBs were between 50-101%,the RSD were all between 5-18%.The recoveries of PCDD/Fs and DL-PCBs for new material alumina of automatic purification column were between 53-92% and RSD from 5 to 23%.The LOQ of PCDD/Fs and DL-PCBs is 0.03-0.33 ng/kg.The z-values of the PT were less than 2.Methods to meet the national standard requirements.The GC-MS/MS screening method of 95 POPs in animal source foods had a good separation in gas chromatography.The correlation coefficient of each POPs is greater than 0.99;and the LOQ were between 0.002-1.0 μg/kg.The average recoveries of 95 POPs were from 45 to 119%,and the RSD is between 11 and 28%.The highest POPs contamination concentration observed in the meat,aquatic products,honey and milk was PAHs,the concentration of PAH-FLU reached 124.89 μg/kg.In the OCPs,the highest mean concentration was 4’4-dicofol,up to 1.02 μg/kg.For different sample kinds,honey had the highest levels of contamination with PAHs,and the highest level of PBDEs contamination were observed in aquatic products,up to 0.41 μg/kg.(3)In the typical area,the contamination level of the four types of animal source food was ranked as pork <milk <eggs <poultry meat,and the maximum measured value of dioxin was 34.31 ng TEQ/ kg fat for chicken.The proportion of free-range chicken and eggs exceeding the EU action limits by 65% and 13%,respectively,much higher than the large-scale breeding of chicken and eggs,and 50% of the free-range chicken around the industrial pollution sources in the B city exceeded the dioxin action limit.The OCDD are the main contributing compounds in the total concentration range from 20-60%;PCB 118 is the main contributing dioxins-like PCBs in chicken,which range from 37-59%.PCB105 and PCB 77 are also important contributing compounds.Dietary exposure risk assessment showed that the total dioxin compound exposure in children and adults through the typical area of contaminated free-range chicken was 4.20 pg/(kg·d)and 7.00pg/(kg·d),respectively,which was 6-10 times of the total daily dietary exposure of general adults in China,and also exceeded the exposure range recommended by the World Health Organization,with a high exposure risk.