Study On The Occurrence Of Chlorinated Paraffins In Placenta Of China General Population By Matrix Solid-Phase Dispersion

Chlorinated paraffins（CPs）are potential persistent organic pollutants（POPs）,and short chian chlorinated paraffins（SCCPs）have been listed in the candidates of POPs under the Stockholm convention（SC）,in 2016,the POPs review committees considered SCCPs to fulfill the criteria of Annex F of the SC.CPs may pose threat to ecological environment and human health,especially for fetuses that have weak defense mechanisms to toxicant,due to their persistence,long-range air transport,bioaccumulation through food web and high toxicological properties.China is the No.1country in the world on CPs production,the risk to the health of residents in our country is more serious than other countries.In this thesis,in order to investigate the exposure level of CPs in China general population,select human placenta as the research target,the pretreatment method for the CPs in human placenta has been developed and the occurrence of CPs in human placentas obtained from China were analyzed using the proposed method.Firstly,the physicochemical properties,analytical methods,sources,releases,the current pollution in environmental matrixes and the ecotoxicity of SCCPs were reviewed.Meanwhile,the matrix solid-phase dispersion extraction method（MSPD）,the placental barrier and the current pollution of POPs in human placenta were summarized.Besides,the significance and the main content of this study were also described.Secondly,a pretreatment method based on matrix solid-phase dispersion（MSPD）using the orthogonal test was developed for the analysis of SCCPs in human placenta by gas chromatograph-electron capture negative ion low-resolution mass spectrometry（GC-ECNI-LRMS）and gas chromatography quadrupole time-of-flight mass spectrometry（GC-QTOF-HRMS）.The optimal conditions as follows:silica gel with the same mass as sample was the optimal dispersing sorbent,44%acidic silica gel can be used as the co-sorbent to remove lipid and eluted by the mixture of hexane and dichloromethane（v:v,7:3,100 mL）.The spiked recoveries of the optimized method were 77.4%and 91.4%for analyzing SCCPs in human placenta by GC-ECNI-LRMS and GC-QTOF-HRMS,and the corresponding relative standard deviations were 10.2%and 5.6%,respectively.The method detection limit（MDL）for the total SCCPs was 36.8 ng/g（dw）and 19.2ng/g（dw）as measured by GC-ECNI-LRMS and GC-QTOF-HRMS,respectively.In a word,the method was suitble for the analysis of CPs in human placenta.Finally,in order to assess the concentration and the congener group profile of CPs in placenta of general population in china,54 human placentas were analyzed by gas chromatography quadrupole time-of-flight mass spectrometry（GC-QTOF-HRMS）.Short-chain CPs（SCCPs）were detected in all samples,theΣSCCPs concentration in the range of 6.8-299.0 ng/g dw（98.5-3770.7ng/g lw）,mean value:38.2 ng/g dw（592.9 ng/g lw）.Medium-chain CPs（MCCPs）were detected in 38 samples,theΣMCCPs concentration in the range of 5.7-51.5 ng/g dw（80.8-954.0 ng/g lw）,mean value:19.5 ng/g dw（316.0 ng/g lw）.SCCPs with 6-7 chlorines predominated in human placentas and mostly focused on the 10-11 carbon chain groups,the most abundant MCCP congener groups were C₁₅H₂₅Cl₇ in most samples.The correlation analysis indicated that there was a significant positive correlation betweenΣSCCPs andΣMCCPs concentrations in placenta samples,and the concentrations ofΣCPs and most CP congener groups had no significant correlations with the gravida^’s age,weight and the baby^’s weight.This is the first investigation of CPs in human placenta,which lay a foundation for evaluating the risk of human exposure especially for the fetus to CPs.