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High polarity analyte(s) in aqueous media: determination of L-PFOA and L-PFOS in ground water
(2022)
The CCQM-K156 comparison was coordinated by TUBITAK UME on behalf of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) for National Measurement Institutes (NMIs) and Designated Institutes (DIs) which provide measurement services in organic analysis under the 'Comité International des Poids et Mesures' Mutual Recognition Arrangement (CIPM MRA).
Perfluoro alkyl substances (PFAS) such as PFOS and PFOA have been used in numerous industrial applications and products. Because of their high stability and resistance to biodegradation, atmospheric photooxidation, direct photolysis and hydrolysis, they are extremely persistent in the environment. The European Union (EU) Water Framework Directive lists PFOS as a priority hazardous substance that poses a significant risk to the aquatic environment. The use of PFOS-containing Aqueous Film-Forming Foams (AFFFs) has been banned since June 2011 in the EU. As relatively water-soluble, effectively non-degradable compounds, PFOS and PFOA migrate to ground water. They are not removed in the conventional drinking water treatment, and therefore cause health risks in polluted areas. The EU Drinking Water Directive and the European Commission has proposed a limit value of 100 ng/L for the sum of 20 PFAS, including PFOS and PFOA.
This study provides the means for assessing measurement capabilities for determination of high polarity measurands in a procedure that requires extraction, clean-up, analytical separation and detection. Successful participation in CCQM-K156 demonstrates measurement capabilities in determining mass fraction of organic compounds, with a molecular mass of 200 g/mol to 700 g/mol, having high polarity pKow -2, in a mass fraction range from 0.5 ng/kg to 500 ng/kg in aqueous media.
Nine NMIs and DIs participated in the CCQM-K156 key comparison. Seven institutes reported their results. SPE was applied in the sample pre-treatment and LC-MS was applied for detection. All participating laboratories applied isotope dilution mass spectrometry (IDMS) techniques for quantification. Participants established the metrological traceability of their results using certified reference materials (CRMs) from NMIs with stated traceability; where commercially available high purity materials were used the purity was determined in-house. The CCQM-K156 results for L-PFOA and L-PFOS range from 2.75 ng/kg to 5.50 ng/kg with a % RSD of 19.5 % for L-PFOA and from 2.04 ng/kg to 4.45 ng/kg with a % RSD of 21.3 % for L-PFOS. The KCRV was assigned using a Hierarchical Bayesian Random Effects Model (HB REM) estimator from the values reported by six of the participants. One participant result of L-PFOS and one result of L-PFOA were excluded from the KCRV for technical reasons. The KCRV was 4.9 ng/kg ± 0.4 ng/kg for L-PFOA and 3.8 ng/kg ± 0.4 ng/kg for L-PFOS. The six institutes that were included in the assignment of consensus KCRV all agreed within their standard uncertainties.
To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.
The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Per- und polyfluorierte Alkylsubstanzen (PFAS) bilden eine sehr komplexe Schadstoffgruppe mit über 6300 Einzelsubstanzen, die in vielfältiger Form in die Umwelt eingetragen werden. Für ein effektives Monitoring dieser Schadstoffklasse benötigt es ein Zusammenspiel aus Summenparameter-Analytik zur hot-spot-Identifizierung und Klassifizierung von Belastungssituationen sowie einer nachgeschalteten target-Analytik zur Identifizierung von Eintragswegen, die zugleich ein tieferes Verständnis von Transformationsprozessen ermöglicht. In diesem Beitrag präsentieren wir eine optimierte Extraktions-Methode für die PFAS-Summenparameteranalytik. Mit Hilfe dieser können bisher verwendete zeit- und kostenintensive Festphasenextraktionen (SPE) umgangen und PFAS-Extraktionseffizienzen gesteigert werden. Die methodische Bestimmungsgrenze (LOQ) war mit 10,30 μg/kg (Fluor pro Bodenprobe) ausreichend für alle 9 untersuchten Realbodenproben.
Per- und polyfluorierte Alkylverbindungen (PFAS) sind sehr persistent und reichern sich in der Umwelt und im menschlichen Organismus in immer höheren Konzentrationen an. PFAS stellen deshalb eine große Gefährdung für Mensch und Umwelt dar. Eingesetzt werden sie u. a. als wasser- und fettabweisende Beschichtung in z. B. der Papier- und Textilindustrie und gelangen so während Produktion, Gebrauch und Entsorgung u. a. in den Wasserkreislauf. PFAS konnten sogar in der arktischen Umwelt in relevanten Konzentrationen detektiert werden und zählen somit zu den „emerging pollutants“. Ein prominenter Vertreter der PFAS stellt Perfluoroctansulfonsäure (PFOS) dar - die jedoch bereits im Anhang des Stockholmer Abkommen gelistet wurde und deren Einsatz somit stark eingeschränkt bzw. verboten ist. Im Hinblick auf die Vielzahl von Verbindungen werden neue analytische Methoden benötigt, die eine PFAS-Belastungssituation möglichst umfassend und nachweisstark widerspiegeln, um zukünftig mögliche Grenzwerte ableiten zu können.
Per- and polyfluorinated alkyl substances (PFASs) are a substance class of over 4730 individual compounds. Several PFASs are extremely persistent, bioaccumulative and toxic. The analysis of PFASs is challenging because of their different chemical and physical properties as well as the high number of target substances. Target-based approaches (e.g., LC-MS/MS) are limited to the availability of analytical grade standards and are not suitable for the analysis of new/unknown PFASs and transformation products. Therefore, PFAS sum parameter methods become increasingly important to indicate a realistic PFAS pollution level.
PFAS sum parameters compromise the proportion of organically bound fluorine that can either be extracted (EOF) or adsorbed to activated carbon (AOF). For the instrumental analysis of such sum parameters, a fluorine selective detector is needed. High resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) is a sensitive and highly selective tool for indirect fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification of c(F) 2.7 µg/L.
Here, we describe a fast and simple extraction method for the determination of the EOF using HR-CS-GFMAS in soil samples. Common approaches for the EOF determination use solid phase extraction (SPE). To omit the bias of this time consuming and expensive step we optimized a fast and simple SPE-free extraction method. The developed extraction method consists of a liquid-solid extraction using acidified methanol. Comparison of the method with and without an SPE clean-up step revealed a drastic underestimation of EOF concentrations using SPE. In the next step, the applicability of our method was tested for other solid matrices. In view of steadily increasing numbers of PFASs, our method will make an important contribution in assessing the pollution situation as well as support policy makers in deriving exposure limits for PFASs in the future.
Per- and polyfluorinated alkyl substances (PFASs) are a group of several thousand individual compounds. Many PFASs are extremely persistent, bioaccumulative and toxic. The analysis of PFASs is challenging because of their various chemical and physical properties as well as the high number of compounds. Target-based approaches (e.g., LC-MS/MS) are limited to the availability of analytical grade standards and are not suitable for the analysis of new/unknown PFASs and transformation products. Therefore, PFAS sum parameter methods become increasingly important to indicate realistic PFAS pollution levels.
PFAS sum parameters display the proportion of organically bound fluorine that can either be extracted (EOF) or adsorbed to activated carbon (AOF). For the instrumental analysis of such sum parameters, a fluorine selective detector is needed. High resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) is a sensitive and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification of c(F) 2.7 µg/L.
In the present work a HR-CS-GFMAS method for EOF analysis was utilized for suspended particulate matter (SPM) analysis in German rivers in time lines from 2005–2020. Therefore, time and spatial resolved trends were investigated. In addition, SPM samples were analyzed for the Σ41PFAS using target analysis based on UHPLC-HRMS. Overall, target analysis drastically underestimated the total PFAS burden in SPM of German rivers compared to the EOF HR-CS-GFMAS analysis. Using a fluorine mass balance approach, only 0.2% to 38.6% of the EOF was explainable using the Σ41PFAS determined with target analysis. Our study highlights the need to integrate PFAS sum parameters (e.g., EOF with HR-CS-GFMAS) in PFAS risk assessment strategies.
Per- und polyfluorierte Alkylverbindungen (PFAS) sind eine Substanzklasse mit über 5200 Verbindungen. Aufgrund der Persistenz, Bioakkumulation in Nahrungsketten, Toxizität und der ubiquitären Verbreitung von PFAS zählen sie zu den „emerging pollutants“. Die PFAS-Analytik ist wegen den vielfältigen physikalisch-chemischen Eigenschaften und der sehr hohen Anzahl an PFAS eine große Herausforderung. Da es für viele Anwendungen noch ungewiss ist, welche PFAS verwendet werden, wie sie in die Umwelt gelangen und welche Transformations- bzw. Abbauprodukte entstehen, stoßen analytische Ansätze, die nur auf Einzelsubstanzen abzielen, hier an ihre Grenzen. Weiterhin wird die Analytik aufgrund der Substitution von bereits regulierten PFAS mit ständig steigenden Anzahlen an PFAS-Verbindungen in der Umwelt konfrontiert. PFAS-Summenparameter-Methoden, die ein nahezu vollständiges Abbild der PFAS-Belastungssituation wiedergeben, werden daher immer wichtiger. In unserer Studie haben wir die zwei meistverwendeten PFAS-Summenparameter, das adsorbierbare organisch gebundene Fluor (AOF) und das extrahierbare organisch gebundene Fluor (EOF), miteinander verglichen. Beide Summenparameter können zur Analyse mit entweder combustion-Ionenchromatographie (CIC) oder hochauflösender Molekülabsorptionsspektrometrie (HR-CS-GFMAS) gekoppelt werden. Hierbei diskutieren wir die Vor- und Nachteile sowohl von beiden Summenparameter- als auch beider Detektions-Methoden. Die Untersuchungen wurden mit Oberflächenwasserproben aus der Spree in Berlin durchgeführt. Neben AOF und EOF wurde auch der Gesamt-Fluorgehalt (TF) mit CIC sowie HR-CS-GFMAS bestimmt. Die Fluor-Massenbilanzierung zeigte, dass das Verhältnis AOF/TF höher als das Verhältnis EOF/TF war. Dabei machte der AOF 0.14–0.81% vom TF und der EOF 0.04–0.28% vom TF aus. Insgesamt war die neue EOF/HR-CS-GFMAS-Methode schneller, präziser und sensitiver als die bereits etablierte AOF/CIC-Methode. Beide Methoden sind vielversprechend für die zukünftige Überwachung von Umweltproben und bilden die Grundlage für mögliche Grenzwerte, die auf die Summe PFAS abzielen.
Here, we describe a fast and simple extraction method for the determination of per- and polyfluorinated alkyl substances (PFASs) utilizing extractable organic fluorine (EOF) sum parameter analysis and high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) in soil samples. After extraction and separation of inorganic and organic fluorinated compounds, organically bound fluorinated compounds were indirectly determined via the molecular absorption of gallium mono-fluoride at 211.248 nm. The implementation of the decisions of the “Stockholm Convention on persistent organic pollutants” as well as the “Protocol on Persistent Organic Pollutants of the Convention on Long-Range Transboundary Air Pollution” of the UNECE include the reduction respectively the elimination of PFASs in the environment. Currently, regulations aim to target single compounds (mostly C8-PFAS). But the PFAS group includes over 4700 substances, which are potentially persistent and toxic, thus target analytical approaches are not suitable for a holistic approach investigating the PFAS pollutant situation. Furthermore, forbidden PFASs are substituted by short-chain PFASs, thus the number of unknow substances is steadily increasing. For this reason, sum parameter approaches are more suitable to investigate and assess the pollution situation as well as derive exposure limits. Our developed analytical method was successfully applied to determine PFASs in soil samples from a polluted site. In view of steadily increasing numbers of PFAS substances, our method will make an important contribution in assessing the pollution situation as well as support policy makers in deriving exposure limits for PFAS in the future.
Here, we describe a fast and simple extraction method for the determination of per- and polyfluorinated alkyl substances (PFASs) utilizing extractable organic fluorine (EOF) sum parameter analysis and high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) in soil samples. After extraction and separation of inorganic and organic fluorinated compounds, organically bound fluorinated compounds were indirectly determined via the molecular absorption of gallium mono-fluoride at 211.248 nm. The implementation of the decisions of the “Stockholm Convention on persistent organic pollutants” as well as the “Protocol on Persistent Organic Pollutants of the Convention on Long-Range Transboundary Air Pollution” of the UNECE include the reduction respectively the elimination of PFASs in the environment. Currently, regulations aim to target single compounds (mostly C8-PFAS). But the PFAS group includes over 4700 substances, which are potentially persistent and toxic, thus target analytical approaches are not suitable for a holistic approach investigating the PFAS pollutant situation. Furthermore, forbidden PFASs are substituted by short-chain PFASs, thus the number of unknow substances is steadily increasing. For this reason, sum parameter approaches are more suitable to investigate and assess the pollution situation as well as derive exposure limits. Our developed analytical method was successfully applied to determine PFASs in soil samples from a polluted site. In view of steadily increasing numbers of PFAS substances, our method will make an important contribution in assessing the pollution situation as well as support policy makers in deriving exposure limits for PFAS in the future.
Per- and polyfluorinated alkyl substances (PFASs) are a group of over 4730 individual compounds. Several PFASs are extremely persistent, bioaccumulative and toxic. The analysis of PFASs is challenging because of their various chemical and physical properties as well as the high number of compounds. Target-based approaches (e.g., LC-MS/MS) are limited to the availability of analytical grade standards and are not suitable for the analysis of new/unknown PFASs and transformation products. Therefore, PFAS sum parameter methods become increasingly important to indicate realistic PFAS pollution levels.
PFAS sum parameters display the proportion of organically bound fluorine that can either be extracted (EOF) or adsorbed to activated carbon (AOF). For the instrumental analysis of such sum parameters, a fluorine selective detector is needed. High resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) is a sensitive and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification of c(F) 2.7 µg/L.
Here, we present an improved method for the determination of PFASs using HR-CS-GFMAS via GaF detection. The optimized method includes a Ga pretreatment as described by Gawor et al. resulting in overall lower detection limits. Furthermore, during optimization the influence of species-specific responses during HR-CS-GFMAS analysis was reduced resulting in a more accurate determination of PFAS sum parameters. To test the applicability of the improved method, we analyzed soil samples from a former fire-fighting training area combining the improved method for detection with our previously optimized extraction method for EOF determination in soils.
Per- and polyfluorinated alkyl substances (PFASs) are a group of over 4730 individual compounds. Several PFASs are extremely persistent, bioaccumulative and toxic. The analysis of PFASs is challenging because of their various chemical and physical properties as well as the high number of compounds. Target-based approaches (e.g., LC-MS/MS) are limited to the availability of analytical grade standards and are not suitable for the analysis of new/unknown PFASs and transformation products. Therefore, PFAS sum parameter methods become increasingly important to indicate realistic PFAS pollution levels.
PFAS sum parameters display the proportion of organically bound fluorine that can either be extracted (EOF) or adsorbed to activated carbon (AOF). For the instrumental analysis of such sum parameters, a fluorine selective detector is needed. High resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) is a sensitive and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification of c(F) 2.7 µg/L.
Here, we present an improved method for the determination of PFASs using HR-CS-GFMAS via GaF detection. The optimized method includes a Ga pretreatment as described by Gawor et al. resulting in overall lower detection limits. Furthermore, during optimization the influence of species-specific responses during HR-CS-GFMAS analysis was reduced resulting in a more accurate determination of PFAS sum parameters. To test the applicability of the improved method, we analyzed soil samples from a former fire-fighting training area combining the improved method for detection with our previously optimized extraction method for EOF determination in soils.
Per- und polyfluorierte Alkylverbindungen (PFAS) sind eine Substanzklasse bestehend aus mehreren tausenden Einzelverbindungen. Unter PFAS zählen alle Verbindungen, die mindestens eine perfluorierte Methyl- (-CF3) oder Methylen-Gruppe (-CF2-) besitzen.[1] Somit zählt auch ein großer Teil der fluorierten Medikamente, Pflanzenschutzmittel oder Biozide in die PFAS-Substanzklasse. Aufgrund der Persistenz, Bioakkumulation in Nahrungsketten, Toxizität und der ubiquitären Verbreitung von PFAS zählen sie zu den „emerging pollutants“.[2] Die PFAS-Analytik ist wegen ihrer vielfältigen physikalisch-chemischen Eigenschaften und der sehr hohen Anzahl an PFAS eine große Herausforderung. Da es für viele Anwendungen noch ungewiss ist, welche PFAS verwendet werden, wie sie in die Umwelt gelangen und welche Transformations- bzw. Abbauprodukte entstehen, stoßen analytische Ansätze, die nur auf Einzelsubstanzen abzielen, hier an ihre Grenzen. PFAS-Summenparameter-Methoden, die darauf abzielen ein möglichst vollständiges Abbild der PFAS-Belastungssituation widerzuspiegeln, werden daher immer wichtiger.
HR-CS-GFMAS turned out to be a sensitive, fast and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) at a temperature of 1550°C. GaF can be detected at 211.248 nm providing limits of quantificationin the low μg/L range. However, several species specific effects where observed when analyzing PFASs.
The combination of non-target analysis (NTA) based on HPLC-ESI-MS with elemental fluorine speciation analysis based on HPLC-PARCI-MS for the identification and quantification of (unknown) organofluorines in environmental samples is associated with several advantages e.g., reduced non-target data treatment workflow and quantification.
PFASs compromise persistent, bioaccumulative, and toxic properties and are hence, environmental contaminants of emerging concern. Thus, procedures for identifying potential sources of the entrance of these compounds into the environment, identification of new organofluorine species, and closing mass balances need urgent development. The intrinsic fluorine tag appears in a sizable fraction of these and other xenobiotics, making elemental speciation desirable for quantitative NTA in these areas. Current non-target approaches based on ESI-HRMS suffer from a lack of data mining algorithms for identification of PFASs with low fluorine mass percentages. Furthermore, low ionization efficiencies of the compounds hamper detection limits.
Hence, the proposed combination of simultaneous HPLC-ESI-MS and HPLC-PARCI-MS via split-stream coupling is a promising approach for environmental PFAS monitoring. Furthermore, it could serve as an important analytical procedure to set up limiting values in compliance with the desired PFAS ban of the European Union.
With the continuous release of anthropogenic pollutants into the environment, substantial risks for the human health arise. Concerning are especially persistent substances (e.g., PFAS) as they accumulate in food chains which inevitably result in the transgression of negative impact threshold levels. Environmental Analytical Chemsitry interfaces all disciplines of Risk Assessment. Therefore it is the important tool to identify, monitor, and remediate environmental pollutants. Based on the example of PFAS, a workflow to tackle environmental pollutants in a retro- and pro-spective way is shown. Within the project, the worldwide situation of environmental pollutants will be illustrated for the example of PFAS. As the major discipline to confront the problem, analytical chemistry will be shown as a key tool for contesting PFAS and creating safe-by-design materials in the future.
Per- and polyfluoroalkyl substances (PFASs) are a group of anthropogenic contaminates associated with persistent, bioaccumulative and toxic properties. Mostly, target-based approaches (e.g., LC-MS/MS) are utilized for the analysis of PFASs in the environment. Target approaches are limited to a few selected PFASs and therefore underestimate the total PFAS burden. Analytical approaches based on total fluorine for PFAS sum parameter analysis become increasingly important to indicate realistic PFAS pollution levels.
Recently high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) turned out to be a sensitive and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification in the low µg F/L range. HR-CS-GFMAS analysis can be combined with the extractable organically bound fluorine (EOF) approach whereas PFASs are extracted from liquid or solid samples using organic solvents and/or solid phase extraction (SPE).
In this presentation the applicability of HR-CS-GFMAS for organic fluorine analysis in various environmental sample including (1) water samples, (2) soil samples and (3) plant samples is demonstrated.
(1) We investigated EOF concentrations in water bodies in Berlin, Germany and used additional PFAS target analysis for a PFAS mass balance approach. EOF concentrations were in the expected range for an urban river system. However, downstream of an effluent discharge, the EOF increased by one order of magnitude from 40 to 574 ng F/L. Target analysis determined mostly short-chained perfluorinated carboxylic acids and sulfonic acids, which however only made up less than 10% of the EOF. This study highlights that EOF screening using HR-CS-GFMAS is useful and advantageous compared to target analysis to identify pollution sites in urban water systems.
(2) For soil samples, we optimized a fast and simple PFAS extraction method for EOF determination. The developed extraction method consists of a liquid-solid extraction without any additional SPE for fluoride removal. We investigated different soil samples using the optimized method with and without an additional SPE clean-up step and revealed a drastic underestimation of EOF mass fractions using SPE. The optimized method is a valuable screening tool for fast PFAS monitoring.
(3) For plant samples, we conducted a study on the uptake and fate of PFASs in bean plants. For PFAS mass balancing HR-CS-GFMAS analysis was combined with LC-MS/MS analysis. PFASs were spiked as mixtures of known and unknown composition. Short-chained PFASs were determined with high mass fractions mainly in the fruits of the investigated plants while long-chained PFASs were mainly determined in roots. Overall, both methods indicate comparable results with target analysis being more reliable for known PFAS contamination and EOF/HR-CS-GFMAS analysis being more valuable to identify PFAS exposure of unknown composition.
Introduction
Per- and polyfluorinated alkyl substances (PFASs) are a group of over 4730 individual compounds. Several PFASs are extremely persistent, bioaccumulative and toxic. The analysis of PFASs is challenging because of their various chemical and physical properties as well as the high number of compounds. Target-based approaches (e.g., LC-MS/MS) are limited to the availability of analytical grade standards and are not suitable for the analysis of new/unknown PFASs and transformation products. Therefore, PFAS sum parameter methods become increasingly important to indicate realistic PFAS pollution levels.
Methods
For the instrumental analysis of such sum parameters, a fluorine selective detector is needed. In our study we used high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) which is a sensitive and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification of c(F) 2.7 µg/L.
Results
Here, we present an improved method for the determination of PFASs using HR-CS-GFMAS via GaF detection. The optimized method includes a modifier pretreatment step using a mixture of Mg, Pd and Zr and a correction measurement using perfluorooctanoic acid. The combination of both resulted in increased accuracy and precision as well as overall lower detection limits. Furthermore, during optimization the influence of species-specific responses during HR-CS-GFMAS analysis was reduced resulting in a more accurate determination of PFAS sum parameters. To test the applicability of the improved method, we analysed soil samples from a former fire-fighting training area combining the improved method for detection with our previously optimized extraction method for extractable organically bound fluorine (EOF) determination in soils.
Innovative aspects
• Highly sensitive and selective method for fluorine/PFASs analysis based on HR-CS-GFMAS
• Increased accuracy for the determination of EOF
• Reduction of PFAS species-specific responses by optimized modifier conditions
HR-CS-GFMAS a new screening tool for per- and polyfluoroalkyl substances (PFAS) in the environment
(2023)
Per- and polyfluorinated alkyl substances (PFASs) are a large group of anthropogenic contaminates. Concerning are especially their persistent, bioaccumulative and toxic properties. Mostly, target-based approaches (e.g., LC-MS/MS) are utilized for the analysis of PFASs in the environment. But these approaches are limited to the availability of analytical grade standards and therefore drastically underestimate the total PFAS burden. Analytical approaches based on total fluorine for PFAS sum parameter analysis become increasingly important to indicate realistic PFAS pollution levels.
PFAS sum parameters display the proportion of organically bound fluorine that can either be extracted (EOF) or adsorbed to activated carbon (AOF). For the instrumental analysis of such sum parameters, a fluorine selective detector is needed. Besides combustion ion chromatography (CIC), high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) is a sensitive and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification in the low µg F L-1 range.
Here, we present a comparison of total fluorine analysis methods – AOF vs. EOF and HR-CS-GFMAS vs. CIC. Therefore, surface water samples from the Spree River in Berlin, Germany were analyzed at 10 locations for total fluorine (TF), AOF and EOF. The AOF made up 0.14–0.81% of TF and the EOF 0.04–0.28% of TF while AOF concentrations were systematically higher. For the instrumental comparison, HR-CS-GFMAS was the more sensitive and precise method for fluorine analysis compared to CIC.
Per- und polyfluorierte Alkylverbindungen (PFAS) sind eine Substanzklasse bestehend aus mehreren tausenden Einzelverbindungen. Unter PFAS zählen alle Verbindungen, die mindestens eine perfluorierte Methyl- (-CF3) oder Methylen-Gruppe (-CF2-) besitzen. Somit zählt auch ein großer Teil der fluorierten Medikamente, Pflanzenschutzmittel oder Biozide in die PFAS-Substanzklasse. Aufgrund der Persistenz, Bioakkumulation in Nahrungsketten, Toxizität und der ubiquitären Verbreitung von PFAS zählen sie zu den „emerging pollutants“. Die PFAS-Analytik ist wegen ihrer vielfältigen physikalisch-chemischen Eigenschaften und der sehr hohen Anzahl an PFAS eine große Herausforderung. Da es für viele Anwendungen noch ungewiss ist, welche PFAS verwendet werden, wie sie in die Umwelt gelangen und welche Transformations- bzw. Abbauprodukte entstehen, stoßen analytische Ansätze, die nur auf Einzelsubstanzen abzielen, hier an ihre Grenzen. PFAS-Summenparameter-Methoden, die darauf abzielen ein möglichst vollständiges Abbild der PFAS-Belastungssituation widerzuspiegeln, werden daher immer wichtiger.