Patch David, O'Connor Natalia, Vereecken Taylor, Murphy Daniel, Munoz Gabriel, Ross Ian, Glover Caitlin, Scott Jennifer, Koch Iris, Sauvé Sébastien, Liu Jinxia, Weber Kela
Environmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON K7K 7B4, Canada.
Brace Water Center, Department of Civil Engineering, McGill University, Montreal, QB H3A 0G4, Canada.
Sci Total Environ. 2024 Jan 20;909:168145. doi: 10.1016/j.scitotenv.2023.168145. Epub 2023 Nov 11.
Per- and polyfluoroalkyl substances (PFAS) encompass over 9000 chemicals utilized in various industrial and commercial applications. However, the quantification of PFAS using standard commercial analytical methods is currently limited to <50 selected compounds. To address this issue, the total oxidizable precursor (TOP) assay was developed, allowing for the oxidative conversion of previously undetectable PFAS precursors into measurable PFAS. This study investigated different sample processing methods to address post-oxidation PFAS loss identified in literature. Using PFOS as a probe molecule, up to 50 % loss of PFOS was identified during sample work-up. It was determined that the use of mass-labelled PFOS and methanolic acetic acid to chemically quench the sample post-oxidation improved PFOS recovery and allowed for correction of any remaining PFOS loss. The use of ultraviolet (UV) light was then investigated as an activator in contrast to the standard thermal activation method. A comparative evaluation was conducted to assess the recovery and conversion of perfluorooctanoic acid (PFOA), PFOS, and 6:2 fluorotelomer sulfonate (6:2 FTS) using both the heat-activated and UV-activated TOP assays. Results demonstrated that the UV-activated TOP assay achieved complete (100 %) oxidation of 6:2 FTS within 7.5 min, resulting in a total yield of generated perfluorinated carboxylic acids (PFCAs) at 108 ± 8 %. The study concluded by investigating the UV-activated TOP assay for its application on various aqueous film forming foam (AFFF) formulations and two AFFF samples drained from military aircraft rescue firefighting vehicles (ARFFVs). Analysis of these AFFF samples were supported by high resolution mass spectrometry and an expanded analytical suite, identifying several fluorotelomer precursors. The findings of this study provide compelling evidence that modifications in sample processing, work-up procedures, expansion of initial PFAS calibration standards, and UV-activation methods enhance the TOP assay, positioning it as a more reliable and quantitative analytical tool for PFAS characterization.
全氟和多氟烷基物质（PFAS）包含9000多种用于各种工业和商业应用的化学品。然而，使用标准商业分析方法对PFAS进行定量目前仅限于<50种选定的化合物。为了解决这个问题，开发了总可氧化前体（TOP）分析方法，该方法可将以前无法检测到的PFAS前体氧化转化为可测量的PFAS。本研究调查了不同的样品处理方法，以解决文献中确定的氧化后PFAS损失问题。以全氟辛烷磺酸（PFOS）作为探针分子，在样品处理过程中发现PFOS损失高达50%。已确定使用质量标记的PFOS和甲醇乙酸在氧化后对样品进行化学淬灭可提高PFOS回收率，并可校正任何剩余的PFOS损失。然后研究了使用紫外线（UV）作为活化剂，与标准热活化方法进行对比。使用热活化和紫外线活化的TOP分析方法进行了比较评估，以评估全氟辛酸（PFOA）、PFOS和6:2氟调聚物磺酸盐（6:2 FTS）的回收率和转化率。结果表明，紫外线活化的TOP分析方法在7.5分钟内实现了6:2 FTS的完全（100%）氧化，生成的全氟羧酸（PFCA）的总产率为108±8%。该研究最后调查了紫外线活化的TOP分析方法在各种水成膜泡沫（AFFF）配方以及从军用飞机救援消防车（ARFFV）中排出的两个AFFF样品上的应用。这些AFFF样品的分析得到了高分辨率质谱和扩展分析套件的支持，鉴定出了几种氟调聚物前体。本研究结果提供了令人信服的证据，表明样品处理、后处理程序的改进、初始PFAS校准标准的扩展以及紫外线活化方法可增强TOP分析方法，使其成为一种更可靠、更定量的PFAS表征分析工具。
