Development Of Analytical Method Of Perfluoroalkyl And Polyfluoroalkyl Substances In Eggs And Their Application As Pollutant Bioindicator

Perfluoroalkyl and Poly-fluoroalkylated substances(PFASs)have been widely produced and used worldwide since the 1950 s due to their excellent performance.PFASs are persistent in the environment and can be detected around the globe as well as human tissues.Perfluorooctanoic acid(PFOA)and perfluorooctanesulfonate(PFOS)are the most widely produced and used PFASs.However,their production and usage have been controlled worldwide since last decades.Therefore,short-chain PFASs and other substitutes have been used on a large scale in recent years,and many novel PFASs have been detected in environmental media and organisms.The high exposure levels and possible adverse outcomes result in an increasing demand for biomonitoring of PFASs.Eggs are the origin of oviparous animal life.On one hand,the level of pollutants in eggs may affect the reproduction of oviparous animals.On the other hand,poultry eggs are rich in nutrients and are one of the main protein sources for human,which are related to human health.There is an increasing number of studies on contamination of PFASs in poultry eggs,their reproductive and developmental toxicity risks,and dietary intake exposure risks.However,these studies are basically concentrated in industrial areas,and there is a lack of research on PFASs in eggs in rural areas.Since the living environment of the free-range chickens and the rural population are highly overlapped,using free-range eggs as a pollutant bioindicator might truly reflect the environmental pollution in rural areas.The first chapter of this thesis summarizes the analysis methods of PFASs in eggs from previous studies,and discusses the advantage and feasibility of eggs as contaminants bioindicators.The matrix effects are high for egg samples in analysis process due to the high abundance of protein and fat.As novel PFASs continue to emerge in the environment,it is necessary to establish an analytical method that can simultaneously determine legacy and novel PFASs in eggs.The second chapter firstly optimized the pretreatment method of PFASs in eggs.Compared with the other two Solid-Phase Extraction(SPE)cartridges(HLB and ENVI-Carb),the WAX cartridge shows great advantages for both legacy and novel PFASs,and the recoveries of 24 PFASs on WAX cartridge ranged from 80.1% to 112%;10 mmol/L Na OH-methanol solution showed the best digestion effect for egg samples with the average recoveries of all PFASs of 97%.The results showed that the optimized method have high sensitivities,good recoveries and reproducibilities,and low matrix effects.In the third chapter,the distribution of PFASs in multiple tissues and organs of hens were analyzed,and the feasibility of using eggs as bioindicators of PFASs was explored.Quantification showed that PFOS was the dominant congener in tissues and organs of hens.The highest concentrations of PFASs were observed in eggs(10.61 ng/g ww)and followed by livers(6.29 ng/g ww).Higher burden of PFASs in eggs compared with other tissues provides the theoretical basis of using eggs as bioindicators of PFASs.Chapter four investigated the occurrence and composition profiles of PFASs in free-range chicken eggs from Tibet,Zhejiang,and Jiangxi Province.Concentrations of legacy and novel PFASs in free-range chicken eggs from Zhejiang were higher than those from Jiangxi and Tibet.In addition,the different composition profiles of PFASs in free-range chicken eggs from the three regions,which were similar to the pollution characteristics in other media in corresponding regions,indicated that free-range chicken eggs could be used as an excellent bioindicator for PFASs in environment and organisms.However,the relative hazard ratio of eggs from Zhejiang was greater than 1 when using the up-to-date suggested value by EFSA in 2020,which indicated that the concentration of PFASs in free-range chicken eggs from Zhejiang region might cause potential health risk to local residents.