Optimization and comparison of several extraction methods for determining perfluoroalkyl substances in abiotic environmental solid matrices using liquid chromatography-mass spectrometry

Are Geotextiles Silent Contributors of Ultrashort Chain PFASs to the Environment?

We investigated the presence of per- and poly fluoroalkyl substances (PFASs) in woven and nonwoven polypropylene geotextiles and four nonwoven polyester geotextiles commonly used in modern geosynthetic composite lining systems for waste containment facilities such as landfills. Targeted analysis for 23 environmentally significant PFAS molecules and methods for examining "PFAS total" concentrations were utilized to assess their occurrence in geotextiles. This analysis showed that most geotextile specimens evaluated in the current investigation contained the ultrashort chain PFAS compound pentafluoropropionic acid (PFPrA). While the concentrations ranged from nondetectable to 10.84 μg/g, the average measured concentrations of PFPrA were higher in polypropylene than in polyester geotextiles. "PFAS total" parameters comprising total fluorine (TF) and total oxidizable precursors (TOPs) indicate that no significant precursor mass nor untargeted intermediates were present in geotextiles. Therefore, this study identified geotextiles as a possible source of ultrashort PFASs in engineered lined waste containment facilities, which may contribute to the overall PFAS total concentrations in leachates or liquors they are in contact with. The findings reported for the first time herein may lead to further implications on the fate and migration of PFASs in geosynthetic composite liners, as previously unidentified concentrations, particularly of ultrashort-chain PFASs, may impact the extent of PFAS migration through and attenuation by constituents of geosynthetic composite liner systems. Given the widespread use of geotextiles in various engineering activities, these findings may have other unknown impacts. The significance of these findings needs to be further elucidated by more extensive studies with larger geotextile sample sizes to allow broader, generalized conclusions to be drawn.

Immobilization of per- and polyfluoroalkyl substances (PFAS): Comparison of leaching behavior by three different leaching tests

The evaluation of PFAS immobilization performance in laboratory experiments, especially the long-term stability, is a challenge. To contribute to the development of adequate experimental procedures, the impact of experimental conditions on the leaching behavior was studied. Three experiments on different scales were compared: batch, saturated column, and variably saturated laboratory lysimeter experiments. The Infinite Sink (IS) test - a batch test with repeated sampling - was applied for PFAS for the first time. Soil from an agricultural field amended with paper-fiber biosolids polluted with various perfluoroalkyl acids (PFAAs; 655 μg/kg ∑¹⁸PFAAs) and polyfluorinated precursors (1.4 mg/kg ∑¹⁸precursors) was used as the primary material (N-1). Two types of PFAS immobilization agents were tested: treatment with activated carbon-based additives (soil mixtures: R-1 and R-2), and solidification with cement and bentonite (R-3). In all experiments, a chain-length dependent immobilization efficacy is observed. In R-3, the leaching of short-chain PFAAs was enhanced relative to N-1. In column and lysimeter experiments with R-1 and R-2, delayed breakthrough of short-chain PFAAs (C4) occurred (> 90 days; in column experiments at liquid-to-solid ratio (LS) > 30 L/kg) with similar temporal leaching rates suggesting that leaching in these cases was a kinetically controlled process. Observed differences between column and lysimeter experiments may be attributed to varying saturation conditions. In IS experiments, PFAS desorption from N-1, R-1, and R-2 is higher than in the column experiments (N-1: +44 %; R-1: +280 %; R-2: +162 %), desorption of short-chain PFAS occurred predominantly in the initial phase (< 14 days). Our findings demonstrate that sufficient operating times are essential in percolation experiments, e.g., in column experiments >100 days and LS > 30 L/kg. IS experiments may provide a faster estimate for nonpermanent immobilization. The comparison of experimental data from various experiments is beneficial to evaluate PFAS immobilization and to interpret leaching characteristics.

Method for extraction and analysis of per- and poly-fluoroalkyl substances in contaminated asphalt

The legacy use of aqueous film-forming foam (AFFF) has led to the generation of large volumes of per- and poly-fluoroalkyl substances (PFAS)-contaminated asphalt materials, especially at airports and fire training areas. The management of such PFAS-contaminated asphalt materials requires an understanding of PFAS concentrations in these materials. This study, therefore, aimed to develop a suitable extraction methodology for the analysis of 22 target PFAS (i.e., carboxylic acids, sulfonic acids and fluorotelomers) in asphalt materials. A series of experiments was conducted to optimise extraction solvent composition, as well as to assess the performance of the chosen method under various conditions (i.e., sonication temperature, PFAS contamination level, asphalt core composition and timing of stable isotope addition used as internal standard). The methanol-based extractants performed best due to their accuracy and precision, which were within the acceptable range (extraction efficiency between 70 and 130% and RSD < 20%). The method which involved three successive extractions with methanol/1% NH₃ by ultrasonication at 25 °C was selected due to its performance and ease of operation. The mean recovery of a vast majority of PFAS was found to be in the acceptable range. Tests on the timing of addition of stable isotope (SI)-labelled PFAS internal standards indicate that the recoveries obtained, regardless of when the stable isotopes were added, were within the acceptable range for PFAS. The accuracy and precision of PFAS recoveries were not affected by PFAS spike level (2 μg kg^-1 and 200 μg kg^-1), as well as sample composition (based on the location of asphalt material in the field). Low RSDs were achieved for asphalt cores collected from a contaminated site covering a wide range of concentrations (from LOQ to 2135 mg kg^-1), demonstrating the suitability of the sample preparation method for real-world samples. The results from the interlaboratory testing were also in good agreement and validated the proposed PFAS extraction and analytical approach.

Anti-oxidant mechanisms of Chlorella pyrenoidosa under acute GenX exposure

GenX, a substitute for perfluorooctanoic acid, has been widely detected in surface water. Due to its bioaccumulation, toxicity and persistence, GenX can cause adverse effects such as oxidative damage on aquatic organisms. To investigate the toxicity of GenX and the anti-oxidant mechanism of algae under acute exposure, the growth, photosynthetic activity and gene expression of Chlorella pyrenoidosa (C. pyrenoidosa) were tested. Results showed that the growth of C. pyrenoidosa was inhibited under acute GenX exposure. The toxicity of GenX increased with time and concentration but was lower than that of the traditional perfluoroalkyl and polyfluoroalkyl substances (PFASs). Furthermore, with the increase of GenX concentration, the production of reactive oxygen species increased, while the level of the anti-oxidant enzyme first increased and then decreased. Changes in photosynthetic parameters also indicated that the photosynthetic system of C. pyrenoidosa was negatively affected by GenX exposure. Transcription analysis revealed that the up-regulation of genes related to the glutathione-ascorbate cycle and photosynthesis is a positive strategy to cope with the oxidative stress caused by acute GenX exposure. Our findings provide new insights into the interactions between emerging PFASs and aquatic organisms at the molecular level.

Evaluation of extraction workflows for quantitative analysis of per- and polyfluoroalkyl substances: A case study using soil adjacent to a landfill

Specific aspects of previously reported extraction workflows, for measurement of per- and polyfluoroalkyl substances (PFAS) in solid matrices, have not been adequately interrogated. The objective of this study was to explore the importance of each workflow step in providing the most appropriate extraction for a comprehensive set of PFAS (51 different species) in soil. We compared different procedures, including two pre-extraction set ups (overnight handling of samples prior to extraction), two extraction solvents (methanol (MeOH), and acetonitrile (ACN)), two extraction solvent volumes (10 mL and 8.5 mL), and two post-extraction cleanup strategies (ENVI-Carb and ion-pair). Of the 51 species targeted, 21 were at quantifiable levels in soil samples collected adjacent to a landfill, of which 13 PFAS were consistently detected among the different extraction workflows. Overall, results showed no significant difference in PFAS concentration between different extraction solvents and cleanup strategies. Perfluoropentanoic acid, perfluorohexanoic acid, and perfluorooctanoic acid had the highest concentrations in all extraction workflows, accounting for nearly 13%, 38%, and 17% of the total monitored PFAS (ΣPFAS), respectively. While final concentration values were similar across methods, recovery and accuracy studies showed that MeOH had the best recovery, with 88% of the isotopically labeled PFAS standards showing extraction recovery within the acceptable range of 80% to 120% (compared to 14% of isotopically labeled PFAS standards in workflows using ACN). Upon examination of additional cleanup steps, 67% of monitored PFAS (out of 51 total PFAS monitored), on average, exhibited higher accuracy (relative error ≤20%) using ENVI-Carb clean up (in comparison with 51% in workflows using ion pair clean up). Results also demonstrated that larger volumes of MeOH (and subsequent re-extractions) did not yield a better recovery, enabling a reduction in overall analysis time and cost in comparison to many published methods.

Suspect, non-target and target screening of emerging pollutants using data independent acquisition: Assessment of a Mediterranean River basin

A single workflow based on three approaches (target, suspected and non-target screening) using liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS) in data independent acquisition mode (DIA) was developed to assess the presence of emerging pollutants (EPs) in water and sediments from a Mediterranean River Basin. Identification of potential contaminants was based on mass accuracy, isotopic ratio pattern, theoretical fragmentation, and retention time using Waters UNIFI software. In the suspect screening against a library containing 2200 components, 68 contaminants were tentatively identified, 6 of which were confirmed and quantified with analytical standards. Non-target screening (NTS) required additional manual processing and the aid of an on-line database (ChemSpider) to tentatively identify compounds. Eprosartan, an antihypertensive drug not included in the library used for suspected screening, was confirmed and semi-quantified. The identification of Eprosartan proved the workflow to be functional for NTS. Target screening of 171 pesticides and 33 pharmaceuticals and personal care products (PPCPs) including the compounds confirmed using suspect (6) and non target (1) screening achieved monitoring of the most abundant contaminants from the head to the mouth of the Turia basin to establish their spatial distribution. QTOF-MS screening versatility with its high-resolution capability allows for a comprehensive assessment of EPs in the aquatic environment.

Perfluoroalkyl substances in the Maltese environment - (II) sediments, soils and groundwater

The presence of perfluoroalkyl substances (PFASs) in sediments and groundwater on the Maltese Islands is reported here for the first time. Sediments and soil samples were collected from 24 sites and groundwater was collected from 10 boreholes. PFASs were extracted from water and solid samples using solid phase extraction. The extracts were then analysed using ultra performance liquid chromatography coupled to mass spectrometry in tandem (UPLC-MS/MS). All sediment, soil and groundwater samples were contaminated with at least one PFAS. PFOS (<LOQ - 5.91 ng/g), PFOA (<LOQ - 0.58 ng/g) and PFDA (<LOQ - 1.05 ng/g) were the major PFASs being detected in 100% of the sediment and soil samples. Meanwhile PFOA (<LOD - 2.68 ng/L) was the PFAS detected in all groundwater samples. The concentrations of PFASs observed in groundwater on the Maltese Islands were below the parameters set by the Directive 98/83/EC.

Occurrence, distribution and behavior of emerging persistent organic pollutants (POPs) in a Mediterranean wetland protected area

The analysis of perfluoroalkyl substances (PFASs) and organophosphate flame retardants (PFRs) in the different environmental compartments of a characteristic coastal wetland, the Albufera Natural Park (Valencia, Spain), is required for understanding the transport, accumulation and fate of these pollutants in an area under high anthropogenic pressure. Samples included 13 wastewater treatment plant influents, 13 effluents, 12 surface water, 19 sediment samples and 10 fish individuals from the Albufera Natural Park and the surrounding area. Tris(2-chloroisopropyl) phosphate (TCIPP) and perfluorooctane sulfonate (PFOS) were at the highest concentrations in water, 330.2 ng L^-1 and 47.8 ng L^-1, respectively. In fish and sediment PFOS was also the most detected while perfluorooctanoic acid (PFOA) was in all types of water. Higher levels of target compounds (mainly PFASs) in wastewater effluents compared to influent suggested both, formation from precursors during treatment and poor removal efficiency. Mean levels of PFOS in water and fish were higher than the environmental quality standards (EQS) established by the European Union Directive 2013/39/EU. The influence of the metropolitan area of Valencia and its surrounding industrial belt could explain the significantly higher levels reported in the northern part (influenced by the Turia River).

Emerging contaminants related to the occurrence of forest fires in the Spanish Mediterranean

Forest fires can be a source of contamination because, among others, of the use of chemicals to their extinction (flame retardants, FRs), or by the production of Polycyclic Aromatic Hydrocarbons (PAHs) derived from high temperature alteration of organic matter. Up to our knowledge, this study is the first to assess the direct (PAHs 16 on the USA EPA's priority list), and indirect [tri- to hepta- brominated diphenyl ethers (PBDEs), organophosphorus flame retardants (PFRs) and perfluoroalkyl substances (PFASs)] contamination related to forest fires. The abundance and distribution of these contaminants were monitored on two Mediterranean hillslopes, one burned and one unburned, near Azuébar (SE Spain). Samples were taken in the foot, middle, and top of the slope, at two depths, and in two environments (under canopy and bare soil). Sediments were collected from sediment fences after erosive rainfall events. Most of the screened compounds were found in both, burned and control hillslopes, though significant differences were found between both. In burned soil, low concentrations of PBDEs (maximum ΣPBDEs: 7.3ngg^-1), PFRs (664.4ngg^-1) and PFASs (56.4ngg^-1) were detected in relation to PAHs (Σ16 PAHs=1255.3ngg^-1). No significant influence of the hillslope position was observed for any of the contaminants but differences based on depth and vegetation presence tended to be significant, particularly for the PAHs. After the first erosive event, concentrations of PBDEs and PAHs were higher in sediment than in soil (ΣPBDEs: 17.8ngg^-1 and Σ16 PAHs=3154.2ngg^-1) pointing out the importance of connectivity processes, especially shortly after fire.

Analysis of the presence of perfluoroalkyl substances in water, sediment and biota of the Jucar River (E Spain). Sources, partitioning and relationships with water physical characteristics

The presence, sources and partitioning of 21 perfluoroalkyl substances (PFASs: C4-C14, C16, C18 carboxylate, C4, C6-C10 sulfonates and C8 sulfonamide) were assessed in water, sediment, and biota of the Jucar River basin (E Spain). Considering the three matrices, perfluoropentanoate (PFPeA) and perfluorooctane sulfonate (PFOS) were the most frequent compounds, being remarkable the high occurrence of short-chain PFASs (C≤8), which are intended to replace the long-chain ones in several industrial and commercial applications. In general, all samples were contaminated with at least one PFAS, with the exception of three fish samples. Mean concentrations detected in sediments (0.22-11.5ng g(-1)) and biota (0.63-274µgkg(-1)) samples were higher than those measured in water (0.04-83.1ngL(-1)), which might suggest (bio) accumulation. The occurrence of PFAS is related to urban and industrial discharges (Cuenca city in the upper part of basin, and car's factory, and effluents of the sewage treatment plant (STP) of Alzira, in the lower part). Increasing pollution gradients were found. On the other hand, higher contamination levels were observed after regulation dams of the catchment pointing out their importance in the re-distribution of these contaminants. None of the hazard quotients (HQ) calculated indicate potential risk for the different tropic levels considered (algae, Daphnia sp. and fish). PFAS concentrations found in this study can be considered in acceptable levels if compared to existing Regulatory Legislation and, consequently, they do not pose an immediate human health risk.

Universal method to determine acidic licit and illicit drugs and personal care products in water by liquid chromatography quadrupole time-of-flight

Pharmaceuticals, illicit drugs and personal care products are emerging contaminants widely distributed in water. Currently, a number of solid-phase extraction (SPE) procedures followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) have been reported. However, target analysis of selected compounds is commonly used whereas other related contaminants present in the sample remain invisible. Carmona et al. [1] described a method for determining 21 emerging contaminants by LC-MS/MS with improved mobile phases. We tested this protocol in combination with high resolution mass spectrometry using a quadrupole time-of-flight (QqTOF) instrument to get a wide non-target screening approach in order to have a broader scope and more practical method for detecting licit and illicit drugs and personal care products than traditional target methods. The essential points in the method are: •The screening capabilities of QqTOF (ABSciex Triple TOF™) are used for detecting and identifying non-target pharmaceuticals and a large number of other emerging contaminants in water.•The quantitative features of the instrument, the Achilles heel of the QqTOF mass spectrometers, are established for few selected compounds.•The method may be applied to identify a large number of emerging contaminants in water. However, pre-validation will be needed to quantify them.

Perfluoroalkyl substances in the Ebro and Guadalquivir river basins (Spain)

Mediterranean rivers are characteristically irregular with changes in flow and located in high population density areas. This affects the concentration of pollutants in the aquatic environments. In this study, the occurrence and sources of 21 perfluoroalkyl substances (PFASs) were determined in water, sediment and biota of the Ebro and Guadalquivir river basins (Spain). In water samples, of 21 analytes screened, 11 were found in Ebro and 9 in Guadalquivir. In both basins, the most frequents were PFBA, PFPeA and PFOA. Maximum concentration was detected for PFBA, up to 251.3 ng L(-1) in Ebro and 742.9 ng L(-1) in Guadalquivir. Regarding the sediments, 8 PFASs were detected in the samples from Ebro and 9 in those from Guadalquivir. The PFASs most frequently detected were PFBA, PFPeA, PFOA and PFOS. Maximum concentration in Ebro samples was, in dry weight, for PFOA (32.3 ng g(-1)) and in Guadalquivir samples for PFBA (63.8 ng g(-1)). For biota, 12 PFASs were detected in fish from the Ebro River and only one (PFOS) in that from Guadalquivir. In the Ebro basin, the most frequents were PFBA, PFHxA, PFOA, PFBS, PFOS and PFOSA. Maximum concentration in Ebro samples was, in wet weight, for PFHxA with 1280.2 ng g(-1), and in Guadalquivir samples for PFOS with 79.8 ng g(-1). These compounds were detected in the whole course of the rivers including the upper parts. In some points contamination was due to point sources mostly related to human activities (e.g. ski resorts, military camps, urban areas.). However, there are also some areas clearly affected by diffuse sources as atmospheric deposition.