Department of Chemistry and Biochemistry, Clarkson University, Potsdam, New York 13699, United States.
Department of Environmental Health Sciences, Stempel College of Public Health, Florida International University (FIU), Miami, Florida 33199, United States.
Anal Chem. 2024 Nov 5;96(44):17506-17516. doi: 10.1021/acs.analchem.4c02480. Epub 2024 Oct 15.
Per- and polyfluoroalkyl substances (PFAS) are highly stable ubiquitous contaminants that have been recently added to the list of regulated chemicals. While methods for PFAS detection exist, analysis is difficult, involving a tedious protocol and expensive instrumentation. Here, we demonstrate the first implementation of a phenoxazine dye as a sensing probe that facilitates rapid and inexpensive detection of representative PFAS, e.g., perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), at sensitivity levels covering the recently established Environmental Protection Agency (EPA) limits. The method comprises an electrode modified with a stable redox film of Meldola blue (MB) in its electropolymerized form (MB), which provides amino sites for electrostatic interactions with PFAS. Long-chain PFAS bind specifically to the MB, inducing a hydrophobic-type cluster formation through ion-pair and F-F interactions. This binding generates concentration-dependent changes in the MB/MB oxidation, enabling rapid and sensitive quantification in a single step with high sensitivity, reaching a limit of detection of 0.4 ppt for PFOS and 1.65 ppt for PFOA. The sensor demonstrates good selectivity toward common interfering compounds like humic acid, sodium chloride and fluoride, metallic ions (Cu, Hg, As), as well as pesticides. In addition to PFOS and PFOA, the sensors can measure other perfluoroalkyl compounds, demonstrating potential as a tool for rapid quantification of a total PFAS index, with affinity for long-chain PFAS. This work highlights the integration of redox receptors into an electrochemical sensor to solve the grand challenge of PFAS analysis using a rapid and inexpensive procedure, with potential for field deployment.
全氟和多氟烷基物质（PFAS）是高度稳定的普遍存在的污染物，最近已被添加到受管制化学品清单中。虽然存在用于检测 PFAS 的方法，但分析很困难，涉及繁琐的方案和昂贵的仪器。在这里，我们首次展示了苯并噁嗪染料作为传感探针的应用，该探针可快速、廉价地检测代表性的 PFAS，例如全氟辛烷磺酸（PFOS）和全氟辛酸（PFOA），其灵敏度水平涵盖了最近制定的美国环保署（EPA）限值。该方法包括在其电聚合形式的 Meldola 蓝（MB）稳定的氧化还原膜上修饰电极，该膜提供与 PFAS 静电相互作用的氨基位点。长链 PFAS 特异性结合到 MB 上，通过离子对和 F-F 相互作用诱导疏水性簇形成。这种结合会导致 MB/MB 氧化的浓度依赖性变化，从而能够在单个步骤中快速、灵敏地定量，对 PFOS 的检测限低至 0.4 ppt，对 PFOA 的检测限低至 1.65 ppt。该传感器对常见的干扰化合物如腐殖酸、氯化钠和氟化物、金属离子（Cu、Hg、As）以及农药表现出良好的选择性。除了 PFOS 和 PFOA 之外，该传感器还可以测量其他全氟烷基化合物，这表明它有潜力成为一种快速定量总 PFAS 指数的工具，对长链 PFAS 具有亲和力。这项工作突出了将氧化还原受体整合到电化学传感器中，以使用快速、廉价的程序解决 PFAS 分析的重大挑战，具有现场部署的潜力。
