Quantitative Determination Of Trace Perfluorooctane Sulfonyl Fluoride In Water Samples Based On LC-MS/MS And Chemical Derivatization

Perfluorooctane sulfonyl fluoride(PFOSF)is the main precursor of perfluorooctane sulfonate(PFOS),which was listed as a new persistent organic pollutant by the Stockholm Convention in 2009.Due to lack of ionizable groups and chromophores,PFOSF is difficult to be detected directly.So there are few studies on its detection and environmental distribution at home and abroad.Based on LC-MS/MS and chemical derivatization technology,this study aims to develop a simple and sensitive PFOSF quantification method and apply it to the determination of the PFOSF content in water samples from a variety of sources.The thesis includes the following three parts:1)Based on the oxidability of the-SO2F group,one effective reductant p-toluene thiophenol was selected to react with PFOSF in acetonitrile,and the product perfluorooctyl sulfonic acid were isolated and prepared with a purity of 99.8%determined by LC-MS and the structure was verified by NMR and high resolution MS.PFOSI is proved to be stable and easy to be ionized,ensuring the feasibility for its quantitative analysis.2)The LC-MS/MS quantitative analysis of trace PFOSF was accomplished by direct derivatization of PFOSF by p-toluene thiophenol in water under pH 7-8 using a standard curve calibrated by internal standard.The method has good linearity in the range of 0.5-100.0 ng L-1 with a linear correlation coefficient of 0.9998.Besides,the method detection limit is 0.02 ng L-1 and the recovery rate with added standard is 83-105%.The method has advantages such as high sensitivity,good reproducibility and low matrix interference,among others.3)With the analytical method above,the trace PFOSF in 70 samples of drinking water,surface water and sewage collected from Hangzhou and Dongyang of Zhejiang province was quantitatively analyzed for the first time.As the results,PFOSF can be widely found in various water samples,with a concentration ranging from 0.16-66 ng L-1.In addition,there are great water source-dependent differences in the content of PFOSF in water samples,which is closely related to industrial and human activities.