Per- and polyfluoroalkyl substances (PFAS) are common contaminants of drinking water globally. Due to their large number and diversity, extractable organofluorine (EOF) has been employed as a sum parameter measurement to capture known and unknown PFAS in environmental samples. However, current methods for determining drinking water EOF perform poorly for trifluoroacetic acid (TFA) and provide limited insights into the nature of unidentified fluorine occurring in samples. To address this, we developed and validated a solid-phase extraction procedure for EOF determination in drinking water with improved TFA recovery, which removes and/or accounts for different species of inorganic fluorine. The method produces two fractions: one containing mostly polar fluorinated substances (e.g., TFA, tetrafluoroborate, and trifluoromethanesulfonate) and another containing longer-chain PFAS. Hexafluorophosphate was distributed across both fractions. Application of the method to Stockholm drinking water revealed a closed fluorine mass balance in fraction I, predominantly (93%) consisting of TFA. In fraction II, however, 67% of the fluorine was unidentified, pointing to unknown fluorinated substance(s) with similar physical-chemical properties to PFAS in this fraction (e.g., perfluorooctanesulfonate). In addition to providing clues for identifying EOF, the method improves estimation of “PFAS Total” for comparison to limits under the European Drinking Water Directive.

Hydrophobic organic contaminants (HOCs) are conventionally screened by matching electron ionization (EI) mass spectra acquired using gas chromatography-mass spectrometry (GC-MS) to reference spectra. However, extensive in-source fragmentation hampers de novo structure elucidation of novel substances that are absent from EI databases. To address this problem, a new method based on GC-atmospheric pressure chemical ionization (APCI) coupled to ion mobility-high resolution mass spectrometry (IM-HRMS) was developed for simultaneous target, suspect, and nontarget screening of HOCs. Of 102 target chemicals, 85.3% produced (quasi-)molecular ions as base peaks, while 71.6% displayed method detection limits lower than those of GC-EI-low resolution MS. The optimized method was applied to standard reference sediment and sediments from the Baltic Sea, an Arctic shelf, and a Norwegian lake. In total, we quantified 56 target chemicals with concentrations ranging from 4.86 pg g-1 to 124 ng g-1 dry weight. Further, using a combination of full scan mass spectrum, retention time, collision cross section (CCS), and fragmentation spectrum, a total of 54 suspects were identified at Confidence Level (CL) 2. Among the remaining features, 169 were prioritized using a halogen-selective CCS cutoff (100 Å2 + 20% mass), leading to annotation of 54 substances (CL ≤ 3). Notably, a suite of fluorotelomer thiols, disulfides, and alkyl sulfones were identified in sediment (CL 1-2) for the first time. Overall, this work demonstrates the potential of GC-APCI-IM-HRMS as a next-generation technique for resolving complex HOC mixtures in environmental samples through exploitation of molecular ions.

Emissions of historical fluorinated processing aids used in fluoropolymer production are known to have contributed significantly to environmental levels of persistent perfluoroalkyl acids (PFAAs). Less is known about emissions of contemporary processing aids and the efficacy of technology used to contain them. To address this, we investigated the occurrence of hexafluoropropylene oxide dimer acid (HFPO-DA) and other per- and polyfluoroalkyl substances (PFAS) in airborne PM10 near a fluoropolymer production plant in the Netherlands. The 20-week high-volume air sampling campaign coincided with installation of emission abatement systems. HFPO-DA levels ranged from below detection limits to 98.66 pg m-3 when the wind came from the plant, and decreased to a maximum of 12.21 pg m-3 postabatement. Lagrangian dispersion modeling using FLEXPART revealed good concordance between measured and modeled HFPO-DA concentrations (Pearson’s r = 0.83, p ≤ 0.05, Wilmott’s d = 0.71, mean absolute error = 3.66 pg m-3), providing further evidence that the plant is a point source. Modeling also suggested that HFPO-DA could undergo long-range atmospheric transport with detectable HFPO-DA air concentrations predicted up to several thousand kilometers away. Besides HFPO-DA, the fluorinated processing aid 6:2 fluorotelomer sulfonate and the suspected polymerization byproducts, hydrogen-substituted perfluoroalkyl carboxylic acids, were also observed, highlighting the complex mixture of PFAS emitted by the plant.

Suspect screening strives to rapidly monitor a large number of substances in a sample using mass spectral libraries. For hydrophobic organic contaminants (HOCs), these libraries are traditionally based on electron ionization mass spectra. However, with the growing use of state-of-the-art mass spectrometers, which often use alternative ionization approaches and separation techniques, new suspect screening workflows and libraries are urgently needed. This study established a new suspect screening library for 1,590 HOCs, including exact mass and a combination of measured and model-predicted values for retention time (RT) and collision cross section (CCS). The accuracy of in silico predictions was assessed using standards for 102 HOCs. Thereafter, using gas chromatography-atmospheric pressure chemical ionization-ion mobility-mass spectrometry, a suspect screening workflow constrained by the full scan mass spectrum of (quasi-)molecular ions (including isotope patterns), RT, CCS, and fragmentation mass spectra, together with a continuous scoring system, was established to reduce false positives and improve identification confidence. Application of the method to fortified and standard reference sediment samples demonstrated true positive rates of 79% and 64%, respectively, with all false positives attributed to suspect isomers. This study offers a new workflow for improved suspect screening of HOCs using multidimensional information and highlights the need to enrich mass spectral databases and extend the applicable chemical space of current in silico tools to hydrophobic substances.

The unique properties of per- and polyfluoroalkyl substances (PFAS) have led to their extensive use in consumer products, including ski wax. Based on the risks associated with PFAS, and to align with PFAS regulations, the international ski federation (FIS) implemented a ban on products containing “C8 fluorocarbons/perfluorooctanoate (PFOA)” at all FIS events from the 2021/2022 season, leading manufactures to shift their formulations towards short-chain PFAS chemistries. To date, most studies characterising PFAS in ski waxes have measured a suite of individual substances using targeted analytical approaches. However, the fraction of total fluorine (TF) in the wax accounted for by these substances remains unclear. In this study, we sought to address this question by applying a multi-platform, fluorine mass balance approach to a total of 10 commercially available ski wax products. Analysis of TF by combustion ion chromatography (CIC) revealed concentrations of 1040–51700 μg F g−1 for the different fluorinated waxes. In comparison, extractable organic fluorine (EOF) determined in methanol extracts by CIC (and later confirmed by inductively-coupled plasma-mass spectrometry and 19F- nuclear magnetic resonance spectroscopy) ranged from 92 to 3160 μg g−1, accounting for only 3–8.8 % of total fluorine (TF). Further characterisation of extracts by cyclic ion mobility-mass spectrometry (IMS) revealed 15 individual PFAS with perfluoroalkyl carboxylic acid concentrations up to 33 μg F g−1, and 3 products exceeding the regulatory limit for PFOA (0.025 μg g−1) by a factor of up to 100. The sum of all PFAS accounted for only 0.01–1.0 % of EOF, implying a high percentage of unidentified PFAS, thus, pyrolysis gas chromatography-mass spectrometry was used to provide evidence of the nature of the non-extractable fluorine present in the ski wax products.

The poorly reversible risks to human health and ecosystems from contamination with per- and polyfluoroalkyl substances (PFAS) have led many researchers and regulators worldwide to call for a classwide ban of these so-called forever chemicals. As part of the EU Chemicals Strategy for Sustainability, the national authorities of five European countries submitted a broad restriction proposal on PFAS under REACH in January 2023. This restriction proposal is unique in its scope by including the vast majority of uses for >10 000 substances that meet the OECD definition of PFAS. (1) In parallel, several countries and multiple states in the United States have proposed or enacted broad PFAS restrictions for all non-essential uses or for specific uses and reporting requirements for a range of consumer products. Although the regulatory frameworks underpinning these restrictions contain many differences, the proposed restrictions have the common objective to ban the intentional use of all PFAS and thus avoid regrettable substitution with other PFAS. Given that the proposed restrictions apply to chemical products and articles (both hereafter termed simply “products”) that are imported from other states, countries, or regions, they may also trigger substitution and an increased demand for supply chain information on a global level. Direct communication with manufacturers and distributors is typically the primary approach for companies to ensure compliance with chemical regulations. Nevertheless, companies and authorities require reliable analytical methods to independently verify supply chain information and capture products that are noncompliant with PFAS restrictions.

As a large group of chemicals with diverse properties, per- and polyfluoroalkyl substances (PFAS) have found extensive application throughout consumer products, including cosmetics. Little is known about the importance of dermal uptake as a human exposure pathway for PFAS. Here we investigate a suite of listed-ingredient and residual PFAS in cosmetic products, along with their dermal bioaccessibility using in vitro incubations with artificial sweat. Concentrations of volatile listed ingredients (including cyclic perfluorinated alkanes, perfluorinated ethers, and polyfluorinated silanes) in three products ranged from 876–1323 μg g⁻¹, while polar listed ingredients (i.e., polyfluoroalkyl phosphate esters [PAPs]) in a single product occurred at up to 2427 μg g⁻¹ (6 : 2/6 : 2 diPAP)). Residual perfluoroalkyl carboxylic acids (PFCAs) were also measured at concentrations ranging from 0.02–29 μg g⁻¹. When listed ingredients were included, our targeted analysis accounted for up to 103% of the total fluorine, while highlighting ambiguous and/or incorrect International Nomenclature of Cosmetic Ingredient (INCI) names used in several products. Bioaccessibility experiments revealed that residual PFCAs readily partitioned to artificial sweat (bioaccessible fractions ranging from 43–76% for detectable substances) while listed ingredients (i.e., PAPs and neutral/volatile PFAS) displayed negligible partitioning. This work provides new insight into the occurrence of PFAS in cosmetic products, while furthering our understanding on their mechanisms of dermal uptake.

High-resolution mass spectrometry (HRMS)-based suspect and nontarget screening has identified a growing number of novel per- and polyfluoroalkyl substances (PFASs) in the environment. However, without analytical standards, the fraction of overall PFAS exposure accounted for by these suspects remains ambiguous. Fortunately, recent developments in ionization efficiency (IE) prediction using machine learning offer the possibility to quantify suspects lacking analytical standards. In the present work, a gradient boosted tree-based model for predicting log IE in negative mode was trained and then validated using 33 PFAS standards. The root-mean-square errors were 0.79 (for the entire test set) and 0.29 (for the 7 PFASs in the test set) log IE units. Thereafter, the model was applied to samples of liver from pilot whales (n = 5; East Greenland) and white beaked dolphins (n = 5, West Greenland; n = 3, Sweden) which contained a significant fraction (up to 70%) of unidentified organofluorine and 35 unquantified suspect PFASs (confidence level 2–4). IE-based quantification reduced the fraction of unidentified extractable organofluorine to 0–27%, demonstrating the utility of the method for closing the fluorine mass balance in the absence of analytical standards.

A growing number of studies have reported that routinely monitored per- and polyfluoroalkyl substances (PFAS) are not sufficient to explain the extractable organic fluorine (EOF) measured in human blood. In this study, we address this gap by screening pooled human serum collected over 3 decades (1986-2015) in Tromsø (Norway) for >5000 PFAS and >300 fluorinated pharmaceuticals. We combined multiple analytical techniques (direct infusion Fourier transform ion cyclotron resonance mass spectrometry, liquid chromatography-Orbitrap-high-resolution mass spectrometry, and total oxidizable precursors assay) in a three-step suspect screening process which aimed at unequivocal suspect identification. This approach uncovered the presence of one PFAS and eight fluorinated pharmaceuticals (including some metabolites) in human serum. While the PFAS suspect only accounted for 2-4% of the EOF, fluorinated pharmaceuticals accounted for 0-63% of the EOF, and their contribution increased in recent years. Although fluorinated pharmaceuticals often contain only 1-3 fluorine atoms, our results indicate that they can contribute significantly to the EOF. Indeed, the contribution from fluorinated pharmaceuticals allowed us to close the organofluorine mass balance in pooled serum from 2015, indicating a good understanding of organofluorine compounds in humans. However, a portion of the EOF in human serum from 1986 and 2007 still remained unexplained.

Incineration is commonly used to dispose of waste contaminated with per- and polyfluoroalkyl substances (PFAS), despite few experimental data supporting the efficacy of this technique. To investigate the prevalence of PFAS in residuals from Swedish municipal waste incineration (MWI) plants, samples of fly ash, bottom ash, and flue gas condensate were collected from 27 of Sweden’s 38 plants and analyzed for 13 perfluoroalkyl acids (PFAAs). ∑₁₃PFAA concentrations ranged from 0.28 to 180 ng/L, 0.22–1.6 μg/kg, and 0.18–38 μg/kg, in condensate, bottom ash, and fly ash, respectively (detection frequencies of 79, 21, and 30%, respectively). Total fluorine (TF) measurements in a subset of samples revealed concentrations of <0.20–11 mg F/L in condensate (n = 8) and 120–5400 μg F/g in ashes (n = 8), the former of which was primarily attributed to inorganic fluorine. Extractable organofluorine (EOF) exceeded ∑₁₃PFAA concentrations by up to 3 orders of magnitude (0.70–16 μg F/g in fly ash [n = 3] and <0.80–9.0 μg F/L for condensate [n = 2]), suggesting that the majority of fluorine occurring in MWI residuals remains unidentified. Collectively, these data demonstrate that despite temperatures exceeding 1000 °C, PFAAs and other fluorinated substances may form and/or persist during incineration and risk being released to the environment via MWI residues.