通过诸如可萃取有机氟(EOF)之类的总和参数与高分辨率连续源-石墨炉分子吸收光谱法(HR-CS-GFMAS)相结合来分析全氟烷基物质和多氟烷基物质(PFAS)在氟敏感性和选择性方面非常有希望。然而,HR-CS-GFMAS方法包括几个干燥和加热步骤,这些步骤可以在分子形成步骤之前导致挥发性PFAS的损失,例如,GaF形成。因此,该方法根据其物理/化学性质导致EOF内的PFAS的强烈辨别,因此与降低的准确性相关。为了减少这种差异并指出现实的PFAS污染值,需要优化用于PFAS分析的HR-CS-GFMAS方法。因此,通过应用系统优化步骤,我们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,我们可以使用改性剂干燥预处理步骤,然后依次注入样品溶液来提高PFAS分析方法的灵敏度。在干燥预处理过程中添加Mg改性剂后,挥发性PFAS的灵敏度得到了最大的提高。因此,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),从而更准确地确定有机氟和参数。该方法提供的仪器LOD和LOQ为β(F)1.71μg/L和5.13μg/L,分别。进一步的验证旨在研究关于水基质的几种基质效应。这里,观察到物质特异性行为。例如,全氟辛酸(PFOA)用作校准剂,在高氯化物浓度(>50mg/L)下显示信号抑制。因此,需要在样品制备期间从分析物中彻底分离Cl以进行准确的和参数分析。
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.