Hayes Heidi, Lutes Chris, Watson Nicola, Benton Diane, Hanigan David J, McCoy Seth, Holton Chase, Bronstein Katherine E, Schumacher Brian, Zimmerman John, Williams Alan
Eurofins Environment Testing Northern California, LLC, Folsom, CA, USA.
Jacobs Engineering, Cary, NC, USA.
Environ Sci Atmos. 2025 Jan 1;5(1):94-109. doi: 10.1039/D4EA00084F.
There is no standard sampling and analysis method for vapor phase per- and polyfluoroalkyl substances (PFAS) that can be routinely applied to soil gas, sewer/conduit gas, and indoor air samples. We have validated a thermal desorption GC/MS/MS method for the measurement of a set of fluorotelomer alcohols and perfluorooctanesulfonamides collected on multi-bed sorbent tubes. Applications to perfluorocarboxylic acids were also evaluated since there is debate regarding under what circumstances these compounds could be observed moving into gas phase. Perfluorooctanoic acid (PFOA) met Method TO-17 calibration requirements when calibrated using National Institute of Standards and Technology (NIST) traceable standard solutions introduced through the thermal desorption system and using multiple reaction monitoring (MRM) transitions based on precursor mass ions identified in the PFOA spectra. However, subsequent detailed studies suggested that PFOA was decomposing during the thermal desorption sample introduction step when comparing two alternative GC/MS sample introduction techniques. The primary peak resulting from the thermal desorption of PFOA standard had spectra consistent with perfluoro-1-heptene (PFHp-1), suggesting that a degradation reaction was occurring. Therefore, the identification of the PFCA compounds in this method is currently subject to a potential positive interference from the corresponding perfluoroalkene and other thermally labile PFAS. Thus, it may be beneficial to limit the application of the thermal desorption GC/MS/MS method to the fluorotelomer alcohols and perfluorooctanesulfonamides and use a parallel solvent extraction approach to quantify the PFCA-related compounds. Method validation including desorption efficiency, second source verification, storage stability and method detection limit tests were successfully completed for the fluorotelomer alcohols and perfluorooctanesulfonamides target analytes.
对于气相全氟和多氟烷基物质（PFAS），目前尚无能够常规应用于土壤气体、下水道/管道气体和室内空气样本的标准采样和分析方法。我们已经验证了一种热脱附气相色谱/三重四极杆质谱法，用于测量在多层吸附剂管上采集的一组氟调聚物醇和全氟辛烷磺酸酰胺。由于对于这些化合物在何种情况下会进入气相存在争议，因此也对该方法在全氟羧酸方面的应用进行了评估。当使用通过热脱附系统引入的、可溯源至美国国家标准与技术研究院（NIST）的标准溶液进行校准，并基于全氟辛酸（PFOA）光谱中识别出的前体质量离子使用多反应监测（MRM）跃迁时，全氟辛酸符合方法TO-17的校准要求。然而，随后的详细研究表明，在比较两种气相色谱/质谱进样技术时，全氟辛酸在热脱附进样步骤中会发生分解。全氟辛酸标准品热脱附产生的主要峰的光谱与全氟-1-庚烯（PFHp-1）一致，这表明发生了降解反应。因此，该方法中全氟羧酸化合物的鉴定目前可能会受到相应全氟烯烃和其他热不稳定PFAS的潜在正干扰。因此，将热脱附气相色谱/三重四极杆质谱法的应用限制在氟调聚物醇和全氟辛烷磺酸酰胺，并使用平行溶剂萃取方法来定量与全氟羧酸相关的化合物，可能是有益的。针对氟调聚物醇和全氟辛烷磺酸酰胺目标分析物，成功完成了包括脱附效率、第二来源验证、储存稳定性和方法检出限测试在内的方法验证。
