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Perfluorocarboxylic acids (PFCAs) are one of the most prominent and studied subgroups of per- and polyfluoroalkyl substances (PFAS), which have attracted great interest in environmental and toxicology research due to their intensive use in combination with their persistence, mobility and potential threat to ecosystems and human health. The standard method to quantify PFCAs in water samples is liquid chromatography. For quantification of ultrashort-chain PFCAs (carbon chain length of two or three carbon atoms) often hydrophilic interaction liquid chromatography or ion chromatography coupled with mass spectrometry is used (e.g. DIN 38407-53). However, there are a lot of laboratories using mass spectrometry coupled to headspace gas chromatography systems (HS-GC-MS), usually to quantify a wide range of volatile organic compounds. While PFCAs themselves are difficult to measure with HS-GC-MS in water samples, this challenge can be solved by derivatizing the acids to more volatile compounds, like esters. This approach could enable laboratories using HS-GC-MS to analyse and monitor PFCAs in environmental water samples. By following this idea, we successfully developed a HS-GC-MS method to quantify PFCAs in ultrapure water. Trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) served as exemplary analytes of PFCAs, which were derivatized with methanol and concentrated sulfuric acid to form methyl esters. The method was optimized by varying different preparation and measurement parameters, leading to limits of detection and quantification in the two-digit ppt-range for all four analytes. The method was then tested on various real water samples, including tap and surface water, groundwater, landfill leachate, treated wastewater and impinger water from a sewage sludge incineration experiment. TFA was the most frequently detected PFCA, with concentrations in the ppt and low ppb range. The detection and quantification of the remaining three PFCAs vary with the sample types and sampling location.
Per- and polyfluoroalkyl substances (PFAS) are among the environmental contaminant groups that have received the most attention in recent years. The heightened concern arises from the fact that their unique molecular peculiarity responsible for widespread use, including in critical applications, simultaneously account for their environmental persistence.
The safe destruction of PFAS in various matrices, such as waste streams, is of great importance to prevent the impact on the environment and human health. The volume of such waste increased following the phase-out regulations of PFAS containing aqueous film-forming foams (AFFF) in numerous countries. Originally intended for firefighting, they are now classified as hazardous/ toxic waste that must be properly destroyed.
Incineration shows high potential for destruction of PFAS in impacted wastes since it can break the strong carbon-fluorine bond. This could potentially lead to completely mineralization of PFAS. However, previous experience with halogenated waste incineration has shown that products of incomplete destruction (PIDs) can be formed if the incineration conditions are insufficient.
In the project „Investigating the Thermal Decomposition of PFAS in a Full-Scale Commercial Hazardous Waste Incinerator” funded by the U.S. Department of Defense’s Strategic Environmental Research and Development Program (SERDP), German, Australian and American partners examine the treatment of PFAS containing waste streams in a full-scale hazardous waste incineration plant to demonstrate the readiness, viability, and level of safety of this destruction method.
Here, we present the results of our first campaign. We focused on the incineration of a contemporary fluorotelomer-based AFFF under varying conditions to evaluate the completeness of PFAS destruction and the potential formation of PIDs. In addition to solid samples (slag, boiler ash and dust) and liquid samples (slag cooling water and scrubber water), flue gas was sampled and analysed.
Per- and polyfluoroalkyl substances (PFAS) were classified as a group of highly concerning chemicals over the last decades. Because of the high persistence of PFAS, their previous use led to contamination of the environment and human population. Due to ongoing use and incomplete remediation or destruction methods, the PFAS background in the environment is growing continuously.
The presence of ultrashort PFAS (with ≤3 carbon atoms) in the environment is often overlooked despite their contributions to PFAS levels. These compounds may directly contaminate the environment and arise from degradation of polyfluorinated compounds as well as incomplete PFAS destruction in certain industrial processes. Nonetheless, few approaches for targeted analysis of ultrashort PFASs have been developed, except for trifluoroacetic acid (TFA). Beside liquid (LC-MS/MS), supercritical fluid (SFC-MS/MS), and ion chromatography (IC-MS)-based systems, gas chromatography coupled with mass spectrometry (GC-MS) is a promising method for detection and quantification of ultrashort PFAS.
The goal of this study was to develop a simple headspace GC-MS method for the quantification of ultrashort perfluorocarboxylic acids (PFCAs) and polyfluorinated alcohols (PFOHs) in water samples. In contrast to PFOHs, functionalization of PFCAs was required for quantification. This was done by esterification with methanol at 80 °C, which can be carried out directly in the headspace GC-MS system.
Moreover, several parameters were optimized to achieve a low limit of quantification (LOQ) for the analytes used: i) The ratio of the aqueous solution, methanol, and available gas phase within the analysis vessel, ii) the concentration of additional acid in esterification mixtures of PFCAs, iii) shaking frequency and iv) shaking time before analysis. After optimizing the procedure, we were able to quantify ultrashort PFCAs and PFOHs. Thus, our developed headspace GC-MS method has the potential to be used as an alternative target analysis for ultrashort-chain PFCAs and PFOHs in various water samples (groundwater, wastewater).
Per- and polyfluoroalkyl substances (PFAS) are often environmentally exposed via discharge through human consumer products, such as ski waxes. In our study we analyzed various ski waxes from the 1980s and 2020s, to determine both the sum parameter values total fluorine (TF), extractable organically bound fluorine (EOF), hydrolysable organically bound fluorine (HOF) as well as targeted PFAS analysis. This showed that modern high-performance waxes contain up to 6 % TF, but also PFAS-free labelled ski waxes contain traces of PFAS with EOF/HOF values in the low mg kg-1 range. With the ban of all fluorine-based waxes with the start of the 2023/2024 winter season this will probably change soon. Moreover, we applied our analysis methods to snow samples from a frequently used cross country ski trail (Kammloipe) in the Ore Mountain region in Germany, assessing the potential PFAS entry/discharge through ski waxes. Melted snow samples from different spots were analyzed by the adsorbable organically bound fluorine (AOF) sum parameter and PFAS target analysis and confirmed the abrasion of the ski waxes into the snow. Moreover, on a PFAS hotspot also soil samples were analyzed, which indicate that PFAS from the ski waxes adsorb after snow melting into the soil.
Ultrashort PFAS (≤ 3 carbon atoms) were overlooked for a long time in analytical monitoring. Beside through the use of these substances, they contribute to the PFAS background in the environment through (environmental/ bio-) degradation and incomplete destruction3 of PFAS with longer carbon chains or other fluorinated compounds. As part of the German-Israeli Cooperation in Water Technology Research project „Detection, quantification, and treatment of per- and polyfluoroalkyl substances in groundwater“ (DEFEAT-PFAS), we are developing an as simple as possible direct headspace (HS-)GC-MS method to detect trifluoroacetic acid (TFA) and perfluoropropanioc acid (PFPrA), as well as trifluoroethanol (TFEtOH), pentafluoropropanol(PFPrOH) and hexafluoroiospropanol (HFIP) in water samples. Here we present the results of the PFAS mentioned in spiked ultrapure water solutions.
This study presents a novel semiquantification approach for nontarget screening (NTS), combining matrix-matched calibration and ionization class-specific average calibration curves (ACCs) to address the lack of analytical reference standards for most per- and polyfluoroalkyl substances (PFAS). Ionization class-specific ACCs for carboxylic and sulfonic acids, sulfonamides, and cationic PFAS result in high accuracy, with median absolute accuracy quotients below 2.27×. The approach was applied to soil impacted by aqueous film-forming foam (AFFF) contamination. A total of 96 tentatively identified PFAS were semiquantified in addition to 28 quantified compounds based on available standards. Semiquantified concentrations exceeded those of target analytes, demonstrating the critical role of this method in capturing broader PFAS contamination. In this case, validation against extractable organofluorine (EOF) showed a 102% closed mass balance. The innovative approach not only enables comprehensive PFAS contamination assessment in complex matrices but also expands the scope of the NTS for environmental monitoring, remediation, and risk assessment of AFFF-contaminated sites.
Aufgrund ihrer einzigartigen molekularen Beschaffenheit werden per- und polyfluorierte Alkylsubstanzen (PFAS) in vielen unterschiedlichen Produkten und Anwendungsgebieten eingesetzt. Da sie generell eine hohe Persistenz aufweisen und je nach individueller Struktur unterschiedlich mobil sind, sind sie mittlerweile in allen Umweltkompartimenten und ubiquitär nachzuweisen. Ihre potenzielle (ökologische) Toxizität birgt dabei erhebliche Umweltrisiken, weshalb PFAS in den letzten Jahren mehr und mehr in den Fokus von Umweltverbänden und -behörden gelangten. Gleichzeitig beschäftigen sich Forschungseinrichtungen mit der möglichst weitreichenden Entfernung aus der Umwelt sowie mit deren (anschließender) Zerstörung.
Im Projekt ER24-4073 „Untersuchung des thermischen Abbaus von PFAS in einer kommerziellen Großanlage zur Verbrennung gefährlicher Abfälle“, welches vom U.S. Department of Defense (DoD ) über das Strategic Environmental Research and Development Program (SERDP) gefördert wird, untersuchen deutsche, australische und amerikanische Partner die Behandlung von PFAS-haltigen Abfallströmen in einer großtechnischen Verbrennungsanlage, um die Einsatzbereitschaft, Machbarkeit und Sicherheit dieser Zerstörungsmethode zu demonstrieren.
The research project focuses on tackling the detection, measurement, and elimination of per- and polyfluoroalkyl substances (PFAS) from polluted groundwater, with a particular emphasis on addressing short (C4-C7) and ultrashort (C1-C3) chain PFAS. Given the widespread use of PFAS in various products, they are commonly found in groundwater near industrial and military sites in Germany and Israel. Moreover, recent regulations limiting the use of long chain PFAS have led industries to shift towards shorter chain alternatives. Hence, our efforts are geared towards refining detection, quantification, and removal methods for short and ultrashort chain PFAS. In terms of detection, ww are developing passive sampling devices capable of collecting and tracking the temporal distribution of PFAS species in groundwater. This will enable us to analyze contaminations in German and Israeli groundwater using cutting-edge analytical techniques. Additionally, contaminated groundwater will undergo a two-stage treatment process aimed at concentrating the relatively low PFAS concentrations using innovative membrane technologies such as closed-circuit reverse osmosis and mixed matrix composite nanofiltration membrane adsorbers. Subsequently, the streams containing higher PFAS concentrations will be treated through coagulation, with the remaining PFAS being adsorbed onto carbonaceous nanomaterials. The outcome of this research will include the creation of advanced tools for detecting, measuring, and eliminating PFAS from polluted groundwater, while also enhancing our understanding of the scope of these contaminations.
Per- and polyfluoroalkyl substances (PFAS) are among the environmental contaminant groups that have received the most attention in recent years. The heightened concern arises from the fact that their unique molecular peculiarity responsible for widespread use, including in critical applications, simultaneously account for their environmental persistence.
The safe destruction of PFAS in various matrices, such as waste streams, is of great importance to prevent the impact on the environment and human health. The volume of such waste increased following the phase-out regulations of PFAS containing aqueous film-forming foams (AFFF) in numerous countries. Originally intended for firefighting, they are now classified as hazardous/ toxic waste that must be properly destroyed.
Incineration shows high potential for destruction of PFAS in impacted wastes since it can break the strong carbon-fluorine bond. This could potentially lead to completely mineralization of PFAS. However, previous experience with halogenated waste incineration has shown that products of incomplete destruction (PIDs) can be formed if the incineration conditions are insufficient.
In the project „Investigating the Thermal Decomposition of PFAS in a Full-Scale Commercial Hazardous Waste Incinerator” funded by the U.S. Department of Defense’s Strategic Environmental Research and Development Program (SERDP), German, Australian and American partners examine the treatment of PFAS containing waste streams in a full-scale hazardous waste incineration plant to demonstrate the readiness, viability, and level of safety of this destruction method.
Here, we present the results of our first campaign. We focused on the incineration of a contemporary fluorotelomer-based AFFF under varying conditions to evaluate the completeness of PFAS destruction and the potential formation of PIDs. In addition to solid samples (slag, boiler ash and dust) and liquid samples (slag cooling water and scrubber water), flue gas was sampled and analysed.
Per- and polyfluoroalkyl substances (PFAS) are a group of more than 12,000 anionic cationic, zwitterionic and neutral anthropologic substances which have been used extensively in a variety of products and industries due to their lipo- and hydrophobic properties, and inert physical and chemical stability. As a result of continuous use of fluorinated consumer products, effluents and sewage sludge from wastewater treatment plants (WWTPs) have been shown to be an important source of PFAS contamination into the environment. While environmental exposure of organic pollutants like PFAS, pesticides and pharmaceuticals have to be avoided, phosphorus from sewage sludge must be used in Germany among other things to produce high-quality P-fertilizers for a circular economy. However, the fate of legacy and emerging PFAS compounds during sewage sludge incineration or pyrolysis is for the most parts still unknown. In particular, PFAS analysis in exhaust air from industrial facilities has not yet been standardized in Germany, which means that no comparable results are available for possible regulation.