Zweigle Jonathan, Schmidt Apollonia, Bugsel Boris, Vogel Christian, Simon Fabian, Zwiener Christian
Department of Geosciences, Environmental Analytical Chemistry, University of Tübingen, Schnarrenbergstraße 94-96, 72076, Tübingen, Germany.
Division 4.3 - Contaminant Transfer and Environmental Technologies, Federal Institute for Materials Research and Testing, Unter Den Eichen 87, 12205, Berlin, Germany.
Anal Bioanal Chem. 2024 Dec;416(29):6799-6808. doi: 10.1007/s00216-024-05590-5. Epub 2024 Oct 12.
Organofluorine mass balance approaches are increasingly applied to investigate the occurrence of per- and polyfluoroalkyl substances (PFAS) and other organofluorines in environmental samples more comprehensively. Usually, complex samples prevent the identification and quantification of every fluorine-containing molecule. Consequently, large unidentified fractions between fluorine sum parameters such as extractable organic fluorine (EOF) and the sum of quantified analytes are frequently reported. We propose using oxidative conversion to separate (unidentified) weakly fluorinated compounds (e.g., pesticides, pharmaceuticals) from PFAA-precursors (perfluoroalkyl chain lengths ≥ C). We show with three organofluorine model substances (flufenamic acid, diflufenican, pantoprazole) that CF-groups or aromatic fluorine can be quantitatively converted to inorganic fluoride and trifluoroacetic acid (TFA) by applying PhotoTOP oxidation (UV/TiO). The principle of fluorine separation in mixtures is demonstrated by the oxidation of the three weakly fluorinated compounds together with the PFAA-precursor 6:2/6:2 fluorotelomer mercaptoalkyl phosphate diester (FTMAP). After oxidation, the products F and TFA were separated from PFCAs (> C) by SPE, and the fractions were analyzed individually. Closed mass balances both with and without the addition of organic matrix were achieved. Eventually, the fluorine balance was verified by total fluorine measurements with combustion ion chromatography (CIC). The proposed methods should be considered a proof of concept to potentially explain unidentified fractions of the EOF, especially if compounds with low fluorine content such as pesticides, pharmaceuticals, and their transformation products contribute largely to the EOF. Future studies are needed to show the applicability to the complexity of environmental samples.
有机氟质量平衡方法越来越多地被用于更全面地研究环境样品中全氟和多氟烷基物质（PFAS）及其他有机氟的存在情况。通常，复杂的样品阻碍了对每个含氟分子的鉴定和定量。因此，经常报道在诸如可提取有机氟（EOF）等氟总量参数与定量分析物总和之间存在大量未鉴定部分。我们建议使用氧化转化法将（未鉴定的）弱氟化化合物（如农药、药物）与PFAA前体（全氟烷基链长度≥C）分离。我们用三种有机氟模型物质（氟芬那酸、双氟芬酸、泮托拉唑）表明，通过应用PhotoTOP氧化（紫外/TiO），CF基团或芳香氟可以定量转化为无机氟化物和三氟乙酸（TFA）。通过将三种弱氟化化合物与PFAA前体6:2/6:2氟调聚物巯基烷基磷酸二酯（FTMAP）一起氧化，证明了混合物中氟分离的原理。氧化后，通过固相萃取（SPE）将产物F和TFA与碳链长度大于C的全氟羧酸（PFCA）分离，并分别对各部分进行分析。在添加和不添加有机基质的情况下都实现了封闭的质量平衡。最终，通过燃烧离子色谱法（CIC）进行的总氟测量验证了氟平衡。所提出的方法应被视为一个概念验证，有可能解释EOF中未鉴定的部分，特别是如果农药、药物及其转化产物等低氟含量化合物对EOF有很大贡献的情况下。未来需要开展研究以证明其对环境样品复杂性的适用性。
