Research On Chromatography-mass Spectrometry Detection Method Of Persistent Organic Pollutants Perfluoroalkane Sulfonyl Fluorides In Environmental Soil

Perfluoroalkane sulfonyl fluorides（PFASFs）are important chemical raw materials and intermediates.The representative compounds perfluorooctane sulfonyl fluoride（PFOSF）and perfluorohexane sulfonyl fluoride（PFHx SF）were listed as new persistent organic pollutants by the Stockholm Convention in 2009 and 2022,respectively.Due to the lack of chromophore and ionizable functional groups,PFASFs cannot be detected by conventional chromatography-mass spectrometry technology.So far,the concentration of PFASFs in environmental soils is still unclear,so it is of great significance to establish an analysis method for PFASFs in soil.Based on chemical derivatization and liquid chromatography-mass spectrometry,a sensitive quantitative analysis method for PFOSF and PFHx SF in soil was established,and it was applied to the analysis of environmental soil for the first time.The main content of this paper can be divided into the following aspects:（1）Analysis method of PFOSF and PFHx SF by liquid chromatography-massspectrometry.Based on the oxidative property of perfluoroalkane sulfonyl fluorides(C_nF_2n+1-SO₂F),PFASFs can be transformed into perfluoroalkyl sulfinic acid(C_nF_2n+1-SO₂H)with better mass spectrometry response by adding chemical derivative reagents,and then a liquid chromatography-mass spectrometry analysis method for PFOSF and PFHx SF was established.A variety of derivatization reagents and reaction systems were investigated,and finally the derivatization method was determined using p-methylthiophenol as the derivatization reagent,triethylamine as the catalyst,and acetonitrile as the reaction solvent.This method can transform PFOSF and PFHx SF into perfluorooctane sulfinic acid（PFOSI）and perfluorohexane sulfinic acid（PFHx SI）,respectively.The derived method has good linearity in the range of 10-500 ng/L with correlation coefficients R²>0.99.In addition,the results show that the method has good derivative efficiency,specificity and stability.（2）Establishment of liquid chromatography-mass spectrometry analysis method for PFOSF and PFHx SF in soil.By optimizing the extraction and enrichment process of target compounds in soil and applying the above method to detect target compounds,the LC-MS method for trace PFOSF and PFHx SF in soil was further established.The optimization results showed that most of the target compounds in soil could be transferred to the extraction solution by two repeated ultrasonic extraction operations.The method validation results showed that the method detection limits for PFOSF and PFHx SF were0.066 and 0.072 ng/g,the method quantification limits were 0.21 and 0.23 ng/g,and the recoveries ranged from 96 to 111%and 72 to 89%,respectively.The matrix effects were slight,and intraday and interday precisions were good.All methodological parameters are in line with the regulations of the European Union and American society of testing materials.（3）Application of detection methods in environmental soils.Three types of soil samples were collected from the fluorine chemical plant in Wuhan City,Hubei Province,the landfill in Hangzhou City,Zhejiang Province,and the industrial area in Dongyang City,Zhejiang Province.The concentrations of PFOSF and PFHx SF in environmental soil was obtained for the first time by using this method.Target compounds could be detected in all soil samples from the fluorine chemical plant,and the concentrations of PFOSF and PFHx SF ranged from 2.7 to 357 ng/g and 0.23 to 30 ng/g,respectively.PFOSF and PFHx SF were also detected in soil samples in Dongyang industrial area,with concentrations ranging from 0.24 to 0.49 ng/g and 0.24 to 21 ng/g,respectively.However,the concentrations of the target compounds in the ordinary urban street samples were all below the quantitative limit of the method,and the pollution degree was relatively light.In addition,it was found that the concentrations of PFOSF and PFHx SF in the constructed wetland soil was relatively high,which could effectively adsorb PFOSF and PFHx SF in the effluent from the sewage treatment plant.The detection rates and concentrations of PFOSF and PFHx SF in the samples around the landfill in Hangzhou City were low,with the highest concentrations being 0.76 and 0.32 ng/g,respectively.The study also conducted environmental risk and human health risk assessments on three types of soil samples.The results showed that some soil samples of the fluoride chemical plant may have high environmental risks and affect the health risks of children,while the rest of the soil samples have low environmental risks and will not cause health risks to humans.