環境中新穎全氟化合物的探測與發現 – 以半導體業廢水為例

Abstract

全氟與多氟烷基物質（Per- and polyfluoroalkyl substances, PFAS）是含有CF2或CF3結構的人造物質，化合物種類多達上萬種，因其穩定性和特殊的物理化學性質，廣泛應用於工業和民生用品。然而，多數PFAS具有持久性、生物累積性和毒性，斯德哥爾摩公約已將全氟辛烷磺酸（Perfluorooctane sulfonate, PFOS）等長鏈PFAS列為持久性有機污染物並禁止使用，工業現已轉向使用新型PFAS替代長鏈PFAS。本研究旨在使用液相層析高解析質譜儀開發無需使用標準品的新型非目標物鑑定方法，用以辨識新興PFAS及其環境降解產物，藉由掌握PFAS獨特的質譜碎片資訊，我們建立了質譜碎片掃描和中性丟失掃描模式，首次運用[SO2NC2H4O]–碎片掃描具磺醯胺乙醇結構的PFAS及中性損失CH2CO2掃描具磺醯胺乙酸結構的PFAS。配製一個品管樣品具有11類亞種共39種PFAS的混合標準品，運用本次開發出來的非目標物鑑定方法，可成功鑑定出混合標準品樣品中36種PFAS，鑑別率達92%。由於半導體產業表示PFAS對於製程的良率至關重要，雖然宣稱已停用PFOS，但其替代物質的資訊仍然有限。我們透過開發之新型鑑定方法，調查了半導體業廢水和其污水處理廠放流水，從採集5家半導體廠的10個廢水樣品中，我們成功鑑定了83種PFAS，涵蓋12類亞群，其中有30種是首次被鑑定之結構，在這些半導體廢水中的主要PFAS化合物是全氟丁烷磺醯胺衍生物，包括全氟丁烷磺醯胺乙醇（Perfluorobutane sulfonamidoethanol, FBSE）、全氟丁烷磺醯胺（Perfluorobutane sulfonamdie, FBSA）和全氟丁烷磺醯胺二乙醇（Perfluorobutane sulfonamido diethanol, FBSEE diol），其最高廢水濃度分別為482 μg/L、141 μg/L與83.5 μg/L。此外，在樣品中還篩測出三種超短鏈全氟烷基酸（Perfluoroalkyl acids, PFAAs），濃度介於0.004 μg/L到 19.9 μg/L之間。半導體業廢水經三個污水處理廠處理後，發現全氟丁烷磺醯胺乙酸（Perfluorobutane sulfonamido acetic acid, FBSAA）系列在放流水濃度顯著提高（65%-82%），顯示生物處理將FBSE轉化為FBSAA。本研究亦對FBSEE diol的中間代謝物進行辨識，藉由實驗室的模擬試驗反應，提出了一種新的FBSEE diol代謝途徑。綜整半導體廢水與放流水中PFAS種類與濃度，全氟丁烷磺醯胺衍生物占90% （1934 μg/L），而過去常獲得關注的全氟烷基酸類僅占10%（205 μg/L），表明新興全氟丁烷磺醯胺衍生物可能成為半導體行業的新趨勢與替代品，並通過污水處理廠之生物降解機制轉化成FBSAA而排入環境。

Per- and polyfluoroalkyl substances (PFAS) are synthetic compounds with at least one perfluorinated methyl (–CF3) or methylene group (–CF2–), comprising over ten thousand types. Their stability and unique properties make them widely used in industrial and consumer products. However, many PFAS are persistent, bioaccumulative, and toxic. The Stockholm Convention has banned long-chain PFAS like perfluorooctane sulfonate (PFOS) as persistent organic pollutants, prompting industries to adopt new PFAS alternatives. This study aimed to develop a novel nontarget approach to identify emerging PFAS and their environmental degradation products by liquid chromatography coupled to high-resolution mass spectrometry. A distinct fragment- based approach has been established to identify the hydrophobic and hydrophilic features of acidic and neutral fluorosurfactants through fragments and neutral losses, including those outside the homologous series. This method introduces the sulfonamido ethanol fragment [SO2NC2H4O]– and the neutral loss of CH2CO2 as novel indicator. In a mixture of PFAS standards, 92% (36 out of 39 compounds across 11 classes) were detectable using the fragment-based nontarget procedure. This demonstrates the method's effectiveness in identifying the hydrophobic and hydrophilic properties of various fluorosurfactants. The semiconductor industry has claimed that PFOS has been eliminated from semiconductor production; however, information about the use of alternative compounds remains limited. Ten sewage samples from 5 semiconductor plants were analyzed with target and nontarget analysis. Among the 83 identified PFAS spanning 12 subclasses, 30 were identified for the first time. The dominant identified PFAS compounds were C4 sulfonamido derivatives, including perfluorobutane sulfonamido ethanol (FBSE), perfluorobutane sulfonamide (FBSA), and perfluorobutane sulfonamido diethanol (FBSEE diol), with maximum concentrations of 482 μg/L, 141 μg/L, and 83.5 μg/L in sewage, respectively. Subsequently, three ultrashort chain perfluoroalkyl acids (PFAAs) were identified in samples, ranging from 0.004 to 19.9 μg/L. Three effluent samples from the associated industrial wastewater treatment plants (WWTPs) were further analyzed. This finding, that the C4 sulfonamido acetic acid series constitutes a significant portion (65%−82%) of effluents from WWTP3 and WWTP4, emphasizes the conversion of fluorinated alcohols to fluorinated acids during aerobic treatment. The identification of the intermediate metabolites of FBSEE diol, further supported by our laboratory batch studies, prompts the proposal of a novel metabolic pathway for FBSEE diol. The total amount of perfluorobutane sulfonamido derivatives reached 1934 μg/L (90%), while that of PFAAs, which have typically received attention, was only 205 μg/L (10%). This suggests that perfluorobutane sulfonamido derivatives are emerging as a new trend in fluorosurfactants used in the semiconductor industry, serving as PFAS precursors and contributing to the release of their metabolites into the environment.