Simon Fabian, von der Au Marcus, Gehrenkemper Lennart, Meermann Björn
Federal Institute for Materials Research and Testing, Division 1.1 - Inorganic Trace Analysis, Richard-Willstätter-Straße 11, 12489, Berlin, Germany.
Federal Institute for Materials Research and Testing, Division 1.1 - Inorganic Trace Analysis, Richard-Willstätter-Straße 11, 12489, Berlin, Germany.
Talanta. 2025 Jan 1;281:126811. doi: 10.1016/j.talanta.2024.126811. Epub 2024 Sep 4.
The analysis of per- and polyfluoroalkyl substances (PFAS) via sum parameters like extractable organic fluorine (EOF) in combination with high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) is highly promising regarding fluorine sensitivity and selectivity. However, the HR-CS-GFMAS method includes several drying and heating steps which can lead to losses of volatile PFAS before the molecular formation step using e.g., GaF formation. Hence, the method leads to a strong discrimination of PFAS within the EOF depending on their physical/chemical properties and is therefore associated with reduced accuracy. To reduce this discrepancy and to indicate realistic PFAS pollution values, an optimization of the HR-CS-GFMAS method for PFAS analysis is needed. Hence, we determined fluorine response factors of several PFAS with different physical/chemical properties upon application of systematic optimization steps. We could therefore improve the method's sensitivity for PFAS analysis using a modifier drying pre-treatment step followed by a sequential injection of sample solutions. The highest improvement in sensitivity of volatile PFAS was shown upon addition of a Mg modifier during drying pre-treatment. Thereby, during optimization the relative standard deviation of fluorine response factors could be reduced from 55 % (initial method) to 27 % (optimized method) leading to a more accurate determination of organofluorine sum parameters. The method provides an instrumental LOD and LOQ of β(F) 1.71 μg/L and 5.13 μg/L, respectively. Further validation aimed to investigate several matrix effects with respect to water matrices. Here, substance-specific behavior was observed. For example, perfluorooctanoic acid (PFOA) which was used as calibrator, showed signal suppressions upon high chloride concentrations (>50 mg/L). Hence, a thorough separation of Cl from analytes during sample preparation is needed for accurate sum parameter analysis.
通过诸如可萃取有机氟（EOF）等总和参数结合高分辨率连续光源石墨炉分子吸收光谱法（HR-CS-GFMAS）分析全氟和多氟烷基物质（PFAS）在氟敏感性和选择性方面极具前景。然而，HR-CS-GFMAS方法包括几个干燥和加热步骤，这可能导致挥发性PFAS在使用例如GaF形成的分子形成步骤之前损失。因此，该方法会根据PFAS的物理/化学性质对EOF中的PFAS产生强烈歧视，从而导致准确性降低。为了减少这种差异并指示实际的PFAS污染值，需要对用于PFAS分析的HR-CS-GFMAS方法进行优化。因此，我们在应用系统优化步骤后确定了几种具有不同物理/化学性质的PFAS的氟响应因子。因此，我们可以通过修饰剂干燥预处理步骤，然后依次注入样品溶液来提高该方法对PFAS分析的灵敏度。在干燥预处理期间添加Mg修饰剂后，挥发性PFAS的灵敏度提高最为显著。由此，在优化过程中，氟响应因子的相对标准偏差可以从55%（初始方法）降低到27%（优化方法），从而更准确地测定有机氟总和参数。该方法的仪器检测限和定量限分别为β(F) 1.71 μg/L和5.13 μg/L。进一步的验证旨在研究几种水基质的基质效应。在此，观察到了物质特异性行为。例如，用作校准物的全氟辛酸（PFOA）在高氯浓度（>50 mg/L）时显示出信号抑制。因此，为了进行准确的总和参数分析，在样品制备过程中需要将Cl与分析物彻底分离。
