全氟與多氟烷基物質（PFAS）是一類具有高度化學穩定性的含氟有機化合物，廣泛應用於工業製程與日常產品。由於其具有環境持久性、生物累積潛勢及可能造成健康影響，近年受到高度關注。傳統目標分析主要針對已知 PFAS 進行定量，對於可進一步轉化為持久性全氟烷基酸之前驅物掌握有限，因此可能低估水樣中 PFAS 前驅物的實際貢獻。本研究建立並優化一套結合超高效液相層析–高解析質譜（UHPLC-HRMS）之總可氧化前驅物測試（TOPA）流程，以評估水樣中可氧化 PFAS 前驅物。本研究使用 27 種市售 PFAS 前驅物標準品進行 TOPA 反應條件最佳化，並建立前驅物–產物莫耳轉化率矩陣。樣品經弱陰離子交換固相萃取（WAX SPE）處理後，以超高液相層析高解析度質譜 (UHPLC-HRMS) 分析 19 種終端氧化產物，包括 11 種全氟烷基羧酸（PFCA）與 8 種全氟烷基磺酸（PFSA）。最佳化結果顯示，在 90 mM K₂S₂O₈、450 mM NaOH、85 °C 及 16 小時反應條件下，可獲得最高總莫耳轉化率 67.4 ± 3.3%。莫耳轉化率矩陣顯示，不同 PFAS 前驅物具有明顯不同的氧化轉化行為。多數前驅物主要生成 PFCA，而 PFSA 的生成較少，且主要與特定磺醯胺類前驅物有關。含氟調聚物類前驅物通常可形成多種短鏈及中鏈 PFCA，顯示單一前驅物可能同時貢獻多種終端氧化產物，此結果可作為實際水樣中前驅物轉化結果判讀的重要依據。將最佳化 TOPA 方法應用於地下水、放流水與飲用水後，觀察到多種 PFAS 於氧化後顯著增加，其中 PFBA、PFPeA 與 PFHxA 在三種水樣中均呈現增加，而 PFNA、PFOA、PFDA、PFBS 與 PFOS 則呈現不同水樣間的特異性變化。結果顯示所分析水樣中存在可氧化 PFAS 前驅物，並證明 TOPA 可作為傳統目標分析的補充工具，以提供水樣中前驅物衍生 PFAS 貢獻的額外資訊。

Per- and polyfluoroalkyl substances (PFAS) are highly stable fluorinated chemicals widely used in industrial and commercial applications. Their environmental persistence, bioaccumulation potential, and possible health effects have raised increasing regulatory concern. Because conventional target analysis mainly focuses on known PFAS, precursor compounds that can transform into persistent perfluoroalkyl acids may be underestimated. In this study, a UHPLC-HRMS-based total oxidizable precursor assay (TOPA) workflow was established and optimized to evaluate oxidizable PFAS precursors in aqueous samples. Twenty-seven commercially available PFAS precursor standards were used to optimize reaction conditions and construct a precursor–product molar conversion yield matrix. Samples were prepared by weak anion-exchange solid-phase extraction (WAX SPE), followed by UHPLC-HRMS determination of 19 terminal oxidation products, including 11 perfluoroalkyl carboxylic acids (PFCA) and 8 perfluoroalkyl sulfonic acids (PFSA). The optimized TOPA condition consisted of 90 mM K₂S₂O₈ and 450 mM NaOH at 85 °C for 16 h, producing the highest total molar conversion yield of 67.4 ± 3.3%. The conversion matrix showed distinct precursor-specific oxidation behaviors. Most precursor standards were transformed predominantly into PFCAs, whereas PFSA formation was limited and mainly associated with selected sulfonamide-related compounds. Fluorotelomer-based precursors generally produced multiple short- and medium-chain PFCA, supporting PFAS precursor interpretation in environment. Application of the optimized TOPA procedure to groundwater, effluent water, and drinking water showed significant post-oxidation increases in several PFAS. PFBA, PFPeA, and PFHxA consistently increased across the investigated matrices, while PFNA, PFOA, PFDA, PFBS, and PFOS showed matrix-specific increases. These findings confirm the presence of oxidizable PFAS precursors and demonstrate that TOPA can complement conventional target analysis by providing additional information on precursor-derived PFAS contributions.

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