Per- and polyfluoroalkyl substances (PFASs) are widely used anthropogenic chemicals. The PFAS class includes almost 5000 registered compounds, but analytical methods are lacking for most PFASs. The total oxidizable precursor (TOP) assay was developed to indirectly quantify unknown PFASs that are precursors to commonly measured perfluoroalkyl acids. To understand the behavior of recently identified per- and polyfluoroalkyl ether acids (PFEAs), including fluorinated replacements and manufacturing byproducts, we determined the fate of 15 PFEAs in the TOP assay. Ten perfluoroalkyl ether acids and a chlorinated polyfluoroalkyl ether acid (F-53B) were stable in the TOP assay and represent terminal products that are likely as persistent as historically used PFASs. Adding perfluoroalkyl ether acids and F-53B to the target analyte list for the TOP assay is recommended to capture a higher percentage of the total PFAS concentration in environmental samples. In contrast, polyfluoroalkyl ether acids with a -O-CFH- moiety were oxidized, typically to products that could not be identified by liquid chromatography and high-resolution mass spectrometry. Application of the TOP assay in its proposed enhanced form revealed high levels of PFEAs, the presence of precursors that form perfluoroalkyl carboxylic acids, and the absence of precursors that form PFEAs in surface water impacted by PFAS-containing wastewater discharges.

中文翻译：

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全可氧化前体测定中的全氟烷基醚酸和多氟烷基醚酸的去向及其对受影响水的分析意义。

全氟烷基物质和多氟烷基物质（PFAS）是广泛使用的人为化学品。PFAS类包括近5000种注册化合物，但是大多数PFAS缺乏分析方法。开展了总可氧化前体（TOP）分析法，以间接量化未知PFAS，这些未知PFAS是通常测量的全氟烷基酸的前体。为了了解最近发现的全氟烷基醚酸和多氟烷基醚酸（PFEA）的行为，包括氟化替代物和制造副产物，我们在TOP分析中确定了15种PFEA的命运。十种全氟烷基醚酸和氯化多氟烷基醚酸（F-53B）在TOP分析中稳定，代表的终端产品可能与历史上使用过的PFAS一样持久。建议将全氟烷基醚酸和F-53B添加到目标分析物列表中以进行TOP分析，以捕获环境样品中较高的总PFAS浓度百分比。相反，具有-O-CFH-部分的多氟烷基醚酸通常被氧化成液相色谱和高分辨率质谱无法鉴定的产物。TOP分析以其提议的增强形式的应用表明，PFEA含量高，在形成全氟烷基羧酸的前体中存在，而在含PFAS废水排放影响的地表水中不存在形成PFEA的前体。通常用于无法通过液相色谱和高分辨率质谱法鉴定的产品。TOP分析以其提议的增强形式的应用表明，PFEA含量高，在形成全氟烷基羧酸的前体中存在，而在含PFAS废水排放影响的地表水中不存在形成PFEA的前体。通常用于无法通过液相色谱和高分辨率质谱法鉴定的产品。TOP分析以其提议的增强形式的应用显示出高水平的PFEA，存在形成全氟烷基羧酸的前体以及不存在受含PFAS废水排放影响的地表水中形成PFEA的前体。