Zhang Chuhui, Hopkins Zachary R, McCord James, Strynar Mark J, Knappe Detlef R U
Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States.
National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.
Environ Sci Technol Lett. 2019;6(11):662-668. doi: 10.1021/acs.estlett.9b00525.
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.
全氟和多氟烷基物质（PFASs）是广泛使用的人为化学品。PFAS类别包括近5000种注册化合物，但大多数PFASs缺乏分析方法。总可氧化前体（TOP）分析方法是为间接定量作为常见测量的全氟烷基酸前体的未知PFASs而开发的。为了解最近鉴定出的全氟和多氟烷基醚酸（PFEAs）的行为，包括氟化替代品和制造副产物，我们在TOP分析中确定了15种PFEAs的归宿。十种全氟烷基醚酸和一种氯化多氟烷基醚酸（F-53B）在TOP分析中是稳定的，代表了可能与历史上使用的PFASs一样持久的终产物。建议将全氟烷基醚酸和F-53B添加到TOP分析的目标分析物列表中，以获取环境样品中总PFAS浓度的更高百分比。相比之下，带有-O-CFH-部分的多氟烷基醚酸被氧化，通常氧化为无法通过液相色谱和高分辨率质谱鉴定的产物。以其提议的增强形式应用TOP分析揭示了受含PFAS废水排放影响的地表水中PFEAs的高水平、形成全氟烷基羧酸的前体的存在以及形成PFEAs的前体的不存在。
