Quantification of Per- and Polyfluoroalkyl Substances from PM2.5 using LC-MS

Particulate matter (PM) is a mixture of solid or liquid particles suspended in a gas. Fine particles with diameters smaller than 2.5 mm (PM_2.5) present a large human health concern because they can penetrate lower into the respiratory tract causing cardiovascular and respiratory diseases and lung cancer. A group of organic compounds previously observed in PM_2.5, per- and polyfluoroalkyl substances (PFAS), are present in a variety of environments. Human exposure to PFAS can lead to reduced immune response, endocrine-disruption, cancer and behavioral disorders. PFAS contain fluorinated alkyl chains and are both hydrophobic and lipophobic making them attractive for many consumer applications such as fast-food packaging, water resistant clothing, nonstick pans, and fire-fighting foams. The accuracy and precision necessary for quantification of PFAS from ambient PM_2.5 extracts is challenging due to its presence in laboratory reagents and equipment. Additionally, the composition of PM_2.5 is complex and PFAS tend to be present at low concentrations, requiring sensitive analytical methods. Advances in the quantification of PFAS using liquid chromatography coupled with mass spectrometry (LC-MS) in ambient PM_2.5 have yielded greater accuracy and precision through the implementation of (1) on-line solid phase extraction (SPE) (2) selective pressurized liquid extraction (SPLE) and (3) instrument modifications. Extraction methods such as on-line SPE and SPLE or modifications to the LC-MS system can improve limits of detection, reduce PFAS background, and increase accuracy and reproducibility.