Utilizing Pine Needles to Temporally and Spatially Profile Per- and Polyfluoroalkyl Substances

Abstract

As concerns continue to mount over exposure to per- and polyfluoroalkyl substances (PFAS), novel methods of profiling their presence and modifications are greatly needed as some have known toxic and bioaccumulative characteristics while others have unknown effects. This task however is not simple as over 5000 PFAS of interest have been named by the Environmental Protection Agency and this list continues to grow daily. In this work, we utilized widely available archived and field-sampled pine needles and a novel non-targeted analytical method to evaluate the temporal and spatial presence of numerous PFAS. Over 70 PFAS were detected in the pine needles from this study, providing information from the last six decades related to PFAS exposure, contamination, and reduction.

Uncovering per- and polyfluoroalkyl substances (PFAS) with nontargeted ion mobility spectrometry–mass spectrometry analyses

“…A feature initially annotated as the cyclic PFOS analog perfluoroethylcyclohexanesulfonate (PFECHS) was found at similar abundance both upstream and downstream of the fluorochemical manufacturer. This compound has been detected in surface water in the Great Lakes and the North and Baltic Seas, as well as in pine needles collected near Raleigh-Durham International Airport in North Carolina (36,59,60). Upon further investigation, it was clear that while PFECHS was likely present, at least five to seven additional unsaturated PFOS (U-PFOS) isomers were also present (fig.…”

“…The LC-IMS-MS platform used in this work has previously been applied to nontargeted PFAS analyses; however, structural elucidation was not possible as fragmentation information was not collected (36)(37)(38). Here, we leveraged the optimized LC-IMS-CID-MS method with size-dependent AIF to collect comprehensive precursor and fragmentation data for all PFAS captured by passive samplers commonly used to screen for algal toxins in aquatic systems deployed in an upstream reservoir and directly downstream from a major fluorochemical manufacturer along the Cape Fear River in North Carolina (58).…”

“…Nontargeted LC-IMS-CID-MS data were collected on an Agilent 6560 IMS-quadrupole time-of-flight (QTOF) coupled with an Agilent 1290 Infinity LC System (Agilent Technologies, Santa Clara, CA). The LC method used here has been previously described (36)(37)(38). Briefly, 2-nl injections were chromatographically separated using a C18 Agilent ZORBAX Eclipse Plus column (2.1 × 50 mm, 1.8 μm) with a flow rate of 0.4 ml/min.…”

“…S1 and S2). The optimized CE ramp was then validated using the same standards as used in development, along with extracts from the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1957 (organic contaminants in nonfortified human serum), livers from C57BL/6 mice dosed with PFOA and GenX, and pine needles containing PFAS (36,53). The optimized CE ramp values are displayed in table S5.…”

“…This dynamic, ramped CE approach was initially implemented for peptide ion fragmentation (33) but has since been applied to other biomolecules such as lipids (34,35). In addition to size-based fragmentation capabilities, the addition of IMS greatly benefited other aspects of PFAS nontargeted analyses including isomer separations, matrix distinction, and identification confidence due to CCS validation (36)(37)(38).…”