Optimized method avoiding solvent-induced response enhancement in the analysis of volatile and semi-volatile polyfluorinated alkylated compounds using gas chromatography–mass spectrometry

Recent advances in mass spectrometry analytical techniques for per- and polyfluoroalkyl substances (PFAS)

The ubiquitous presence of per- and polyfluoroalkyl substances (PFAS) in various environments has led to increasing concern, and these chemicals have been confirmed as global contaminants. Following the chemical regulatory restrictions imposed, PFAS alternatives that are presumed to be less toxic have been manufactured to replace the traditional ones in the market. However, owing to the original release and alternative usage, continuous accumulation of PFAS has been reported in environmental and human samples, with uncertain consequences for ecosystem and human health. It is crucial to promote and improve existing analytical techniques to facilitate the detection of trace amounts of PFAS in diverse environmental matrices. This review summarizes analytical methods that have been applied to and advanced for targeted detection and suspect screening of PFAS, which mainly include (i) sampling and sample preparation methods for various environment matrices and organisms, and quality assurance/quality control during the analysis process, and (ii) quantitative methods for targeted analysis and automated suspect screening strategies for non-targeted PFAS analysis, together with their applications, advantages, shortcomings, and need for new method development.

Perfluoroalkyl acids and their precursors in indoor air sampled in children's bedrooms

The contamination levels and patterns of perfluoroalkyl acids (PFAAs) and their precursors in indoor air of children's bedrooms in Finland, Northern Europe, were investigated. Our study is among the most comprehensive indoor air monitoring studies (n = 57) and to our knowledge the first one to analyse air in children's bedrooms for PFASs (17 PFAAs and 9 precursors, including two acrylates, 6:2 FTAC and 6:2 FTMAC). The most frequently detected compound was 8:2 fluorotelomer alcohol (8:2 FTOH) with the highest median concentration (3570 pg/m³). FTOH concentrations were generally similar to previous studies, indicating that in 2014/2015 the impact of the industrial transition had been minor on FTOH levels in indoor air. However, in contrast to earlier studies (with one exception), median concentrations of 6:2 FTOH were higher than 10:2 FTOH. The C8 PFAAs are still the most abundant acids, even though they have now been phased out by major manufacturers. The mean concentrations of FOSE/As, especially MeFOSE (89.9 pg/m³), were at least an order of magnitude lower compared to previous studies. Collectively the comparison of FTOHs, PFAAs and FOSE/FOSAs with previous studies indicates that indoor air levels of PFASs display a time lag to changes in production of several years. This is the first indoor air study investigating 6:2 FTMAC, which was frequently detected (58%) and displayed some of the highest maximum concentrations (13 000 pg/m³). There were several statistically significant correlations between particular house and room characteristics and PFAS concentrations, most interestingly higher EtFOSE air concentrations in rooms with plastic floors compared to wood or laminate.

Emissions of Per- and Polyfluoroalkyl Substances in a Textile Manufacturing Plant in China and Their Relevance for Workers' Exposure

The manufacturing of high-performance fabrics requires numerous chemical treatment steps that involve the use of per- and polyfluoroalkyl substances (PFASs) to protect apparel against water, stain, and oil penetration. However, air and wastewater emissions of PFASs generated during this manufacturing are a potential threat to both factory workers and the environment. We investigated the occurrence and distribution of PFASs in wastewater, air, airborne particles, and settled dust in a textile manufacturing plant in China. PFOA and PFDA or their precursor compounds 8:2 FTOH and 10:2 FTOH were the dominant compounds in all environmental media tested, revealing that long-chain PFASs were preferably used for the manufacturing of functional garments. Besides, PFASs were detected along the textile manufacturing chain, indicating that they were used as durable water repellents and as surfactants in, for example, coating agents. The workers' exposure to FTOHs via air inhalation was up to 5 orders of magnitude higher than the background exposure of the general western population. To the best of our knowledge, this is the first study providing information regarding the emission of PFASs during the manufacturing of textiles via various environmental media.

Poly- and perfluoroalkyl substances (PFASs) in indoor dust and food packaging materials in Egypt: Trends in developed and developing countries

PFASs concentrations in dust samples collected from three microenvironments in Cairo ranged from 1.3 to 69 ng g(-1) with FTOHs being dominant. The 8:2 FTOH was detected in all samples. Among the FOSAs and FOSEs the MeFOSE was dominant while among ionic PFASs, PFOS and PFOA were most prominent. The concentrations of PFASs were among the lowest worldwide. Correlations between worldwide concentrations of PFOS + PFOA and country development indexes highlight higher usage and human exposure in more developed countries. Food packaging was analyzed for PFSAs, PFCAs and PAPs. The 6:2 and 8:2 monoPAPs were found to be above the MDL in 18% of the samples. PFOA was detected in 79% of the samples with median concentration of 2.40 ng g(-1). PFOS was detected in 58% of the samples with median concentration of 0.29 ng g(-1) while PFHxS and PFDS were below detection limit. Different human exposure scenarios were estimated.

Detecting a wide range of environmental contaminants in human blood samples--combining QuEChERS with LC-MS and GC-MS methods

Exposure to environmental pollution and consumer products may result in an uptake of chemicals into human tissues. Several studies have reported the presence of diverse environmental contaminants in human blood samples. However, previously developed multi-target methods for the analysis of human blood include a fairly limited amount of compounds stemming from one or two related compound groups. Thus, the sample preparation method QuEChERS (quick easy cheap effective rugged and safe) was tested for the extraction of 64 analytes covering a broad compound domain followed by detection using liquid and gas chromatography coupled to mass spectrometry (LC- and GC-MS). Forty-seven analytes showed absolute recoveries above 70% in the first QuEChERS step, being a simple liquid-liquid extraction (LLE) using acetonitrile and salt. The second QuEChERS step, being a dispersive solid phase extraction, did not result in an overall improvement of recoveries or removal of background signals. Using solely the LLE step, eight analytes could subsequently be detected in human blood samples from the German Environmental Specimen Bank. Using a LC-multiple reaction monitoring (MRM) method with a triple quadrupole instrument, better recoveries were achieved than with an older LC-high-resolution (HR) MS full scan orbitrap instrument, which required a higher concentration factor of the extracts. However, the application of HRMS full scan methods could be used for the detection of additional compounds retrospectively.

The fate of per- and polyfluoroalkyl substances within a melting snowpack of a boreal forest

Per- and polyfluoroalkyl substances (PFAS) were measured systematically in a snowpack in northern Sweden to determine chemical behaviour during seasonal melt. Average PFAS concentrations were generally low, but displayed a wide range with median (range) concentrations of PFOA and PFOS of 66.5 pg L(-1) (ND-122) and 20.5 pg L(-1) (2.60-253) respectively. Average concentrations of the shorter chain, C4 and C5 perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), were ∼10-fold higher. Differences in the PFAS concentrations and profile were observed between surface snow and deeper layers, with evidence of PFAS migration to deeper snow layers as melt progressed. Chemical loads (ng m(-2)) for C4-9 PFCAs decreased gradually as melt progressed, but increased for C4, C6-8 PFSAs and the longer chain C10-12 PFCAs. This enrichment in the diminishing snowpack is an unusual phenomenon that will affect PFAS elution with meltwater and subsequent entry to catchment surface waters.

Neutral polyfluoroalkyl substances in the global atmosphere

Concentrations of neutral per- and polyfluoroalkyl substances (nPFAS) in the atmosphere are of interest because nPFAS are highly mobile percursors for perfluoroalkyl acids. Two calibration studies in Ontario, Canada and Costa Rica established the feasibility of using XAD 2-resin based passive air samplers (XAD-PAS) to reliably determine long term average air concentrations of nPFAS under temperate and tropical climatic conditions. The temporal and spatial distribution of nPFAS was investigated by analyzing XAD-PAS deployed for one year at between 17 and 46 sites on six continents between 2006 and 2011 as part of the Global Atmospheric Passive Sampling (GAPS) study. Higher levels of fluorotelomer alcohols (FTOHs) compared to fluorinated sulfonamides (FOSAs), and fluorinated sulfonamidoethanols (FOSEs) were observed at all sites. Urban sites had the highest levels of nPFAS compared to rural and remote sites, which is also apparent in a positive correlation of nPFAS levels with the proximity of a sampling site to areas of high population density. Levels of FOSAs and FOSEs tended to decrease during the six years of measurements, whereas an initial decline in the concentrations of FTOHs from 2006 to 2008 did not continue in 2009 to 2011. A comparison of nPFAS levels measured in national XAD-PAS networks in Costa Rica and Botswana revealed that the GAPS sites in Tapanti and the Kalahari are representative of the more remote regions in those countries. XAD-PAS derived absolute nPFAS levels at GAPS sites are lower than those measured using another PAS, but are within the range of levels measured with active air samplers. Agreement of relative nPFAS composition is better between samplers, suggesting that the discrepancy is due to uncertain sampling rates.

Neutral poly- and perfluoroalkyl substances in air and seawater of the North Sea

Concentrations of neutral poly- and perfluoroalkyl substances (PFASs), such as fluorotelomer alcohols (FTOHs), perfluoroalkane sulfonamides (FASAs), perfluoroalkane sufonamidoethanols (FASEs), and fluorotelomer acrylates (FTACs), have been simultaneously determined in surface seawater and the atmosphere of the North Sea. Seawater and air samples were taken aboard the German research vessel Heincke on the cruise 303 from 15 to 24 May 2009. The concentrations of FTOHs, FASAs, FASEs, and FTACs in the dissolved phase were 2.6-74, <0.1-19, <0.1-63, and <1.0-9.0 pg L(-1), respectively. The highest concentrations were determined in the estuary of the Weser and Elbe rivers and a decreasing concentration profile appeared with increasing distance from the coast toward the central part of the North Sea. Gaseous FTOHs, FASAs, FASEs, and FTACs were in the range of 36-126, 3.1-26, 3.7-19, and 0.8-5.6 pg m(-3), which were consistent with the concentrations determined in 2007 in the North Sea, and approximately five times lower than those reported for an urban area of Northern Germany. These results suggested continuous continental emissions of neutral PFASs followed by transport toward the marine environment. Air-seawater gas exchanges of neutral PFASs were estimated using fugacity ratios and the two-film resistance model based upon paired air-seawater concentrations and estimated Henry's law constant values. Volatilization dominated for all neutral PFASs in the North Sea. The air-seawater gas exchange fluxes were in the range of 2.5×10(3)-3.6×10(5) pg m(-2) for FTOHs, 1.8×10(2)-1.0×10(5) pg m(-2) for FASAs, 1.1×10(2)-3.0×10(5) pg m(-2) for FASEs and 6.3×10(2)-2.0×10(4) pg m(-2) for FTACs, respectively. These results suggest that the air-seawater gas exchange is an important process that intervenes in the transport and fate for neutral PFASs in the marine environment.

Recent developments in methods for analysis of perfluorinated persistent pollutants

Perfluoroalkyl substances (PFASs) are proliferated into the environment on a global scale and present in the organisms of animals and humans even in remote locations. Persistent organic pollutants of that kind therefore have stimulated substantial improvement in analytical methods. The aim of this review is to present recent achievements in PFASs determination in various matrices with different methods and its comparison to measurements of Total Organic Fluorine (TOF). Analytical methods used for PFASs determinations are dominated by chromatography, mostly in combination with mass spectrometric detection. However, HPLC may be also hyphenated with conductivity or fluorimetric detection, and gas chromatography may be combined with flame ionization or electron capture detection. The presence of a large number of PFASs species in environmental and biological samples necessitates parallel attempts to develop a total PFASs index that reflects the total content of PFASs in various matrices. Increasing attention is currently paid to the determination of branched isomers of PFASs, and their determination in food.

Figure

Polyfluorinated compounds in the atmosphere along a cruise pathway from the Japan Sea to the Arctic Ocean

Neutral polyfluorinated alkyl substances (PFASs) were measured in high-volume air samples collected on board the research vessel Snow Dragon during the 4th Chinese National Arctic Expedition from the Japan Sea to the Arctic Ocean in 2010. Four volatile and semi-volatile PFASs (fluorotelomer alcohols (FTOHs), fluorotelomer acids (FTAs), perfluoroalkyl sulfonamides (FASAs), and sulfonamidoethanols (FASEs)) were analyzed respectively in the gas and particle phases. FTOHs were the dominant PFASs in the gas phase (61-358pgm(-3)), followed by FTAs (5.2-47.9pgm(-3)), FASEs (1.9-15.0pgm(-3)), and FASAs (0.5-2.1pgm(-3)). In the particle phase, the dominant PFAS class was FTOHs (1.0-9.9pgm(-3)). The particle-associated fraction followed the general trend of FASEs>FASAs>FTOHs. Compared with other atmospheric PFAS measurements, the ranges of concentrations of ∑FTOH in this study were similar to those reported from Toronto, north America (urban), the northeast Atlantic Ocean, and northern Germany. Significant correlations between FASEs in the gas phase and ambient air temperature indicate that cold surfaces such as sea-ice, snowpack, and surface seawater influence atmospheric FASEs.

Indoor and outdoor poly- and perfluoroalkyl substances (PFASs) in Korea determined by passive air sampler

Despite concerns to their increasing contribution to ecological and human exposure, the atmospheric levels of poly- and perfluoroalkyl substances (PFASs) have been determined mainly in Europe and North America. This study presents the indoor and outdoor air concentrations of volatile PFASs [fluorotelomer alcohols (FTOHs), and perfluoroalkyl sulfonamides/sulfonamidoethanols/sulfonamide ethyl acetate (FOSAs/FOSEs/FOSEA)] for the first time in Korean cities. In contrast to the good agreement observed for indoor FTOHs levels in Korea and Europea/North America, FOSAs/FOSEs levels were 10-100-fold lower in Korean indoor air, representing a cultural difference of indoor source. Korean outdoor air contained higher PFAS levels than indoor air, and additionally showed different PFAS composition profile from indoor air. Thus, indoor air would not likely be a main contributor to atmospheric PFAS contamination in Korea, in contrast to western countries. Inhalation exposure of volatile PFASs was estimated to be a minor contributor to PFOA and PFOS exposure in Korea.

Determination of perfluorinated chemicals in food and drinking water using high-flow solid-phase extraction and ultra-high performance liquid chromatography/tandem mass spectrometry

For this study, we developed methods of determining ten perfluorinated chemicals in drinking water, milk, fish, beef, and pig liver using high-flow automated solid-phase extraction (SPE) and ultra-high performance liquid chromatography/tandem mass spectrometry. The analytes were separated on a core-shell Kinetex C18 column. The mobile phase was composed of methanol and 10-mM N-methylmorpholine. Milk was digested with 0.5 N potassium hydroxide in Milli-Q water, and was extracted with an Atlantic HLB disk to perform automated SPE at a flow rate ranged from 70 to 86 mL/min. Drinking water was directly extracted by the SPE. Solid food samples were digested in alkaline methanol and their supernatants were diluted and also processed by SPE. The disks were washed with 40% methanol/60% water and then eluted with 0.1% ammonium hydroxide in methanol. Suppression of signal intensity of most analytes by matrixes was lower than 50%; it was generally lower in fish and drinking water but higher in liver. Most quantitative biases and relative standard deviations were lower than 15%. The limits of detection for most analytes were sub-nanograms per liter for drinking water and sub-nanograms per gram for solid food samples. This method greatly shortened the time and labor needed for digestion, SPE, and liquid chromatography. This method has been applied to analyze 14 types of food samples. Perfluorooctanoic acid was found to be the highest among the analytes (median at 3.2-64 ng/g wet weight), followed by perfluorodecanoic acid (0.7-25 ng/g) and perfluorododecanoic acid (0.6-15 ng/g).

Indoor sources of poly- and perfluorinated compounds (PFCS) in Vancouver, Canada: implications for human exposure

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are widely detected in human blood and serum and are of concern due to their potential toxicity. This study investigated the indoor sources of these compounds and their neutral precursors through a survey of 152 homes in Vancouver, Canada. Samples were collected of indoor air, outdoor air, indoor dust, and clothes dryer lint and analyzed for neutral [i.e., fluorotelomer alcohols (FTOHs), perfluorooctane sulfonamide (FOSA), and perfluorooctane sulfonamidoethanol (FOSE)] and ionic [i.e., PFOS and perfluoroalkyl carboxylates (PFCAs)] poly- and perfluorinated compounds (PFCs). Indoor air was dominated by 8:2 FTOH with a geometric mean concentration (pg/m(3)) of 2900. Among the FOSAs and FOSEs, MeFOSE exhibited the highest air concentration with a geometric mean of 380 pg/m(3). PFOA was the major ionic PFC and was detected in all indoor air samples with a geometric mean of 28 pg/m(3), whereas PFOS was below the detection limit. The results for the ionic PFCs in indoor air are the first for North America. The pattern of the neutral PFCs in house dust was also dominated by 8:2 FTOH, with a geometric mean of 88 ng/g. Dusts were enriched (relative to air) with sulfonamidoethanol (FOSE) which comprised ∼22% of the total neutral PFC content compared to only ∼3% in air. PFOS and PFOA were the most prominent compounds detected in dust samples. Levels of neutral PFCs in clothes dryer lint were an order of magnitude lower compared to house dust. Human exposure estimates to PFCs for adults and children showed that inhalation was the main exposure route for neutral and ionic PFCs in adults. For toddlers, ingestion of PFCs via dust was more relevant and was on the order of a few mg/day. Results from this study contribute to our understanding of exposure pathways of PFCs to humans. This will facilitate investigations of related health effects and human monitoring data.

Per- and polyfluorinated compounds in house dust and indoor air from northern Norway - a pilot study

Polyfluorinated compounds (PFCs) are an extremely versatile class of compounds and are used in a variety of consumer applications and products. Recent studies have suggested that PFCs in indoor air and dust could act as sources of human exposure and outdoor air contamination. This study presents method development and analysis of a wide range of PFCs in dust and air using active sampling techniques with commercially available sampling equipment (forensic nozzles with filter housings for dust collection and polyurethane foam (PUF)-XAD(2)-PUF sandwich-tubes for air sampling) using both liquid and gas chromatography mass spectrometry. The developed method was validated and tested for applicability to analyze dust and air samples at both low and high concentrations (0.5 ng and 25 ng per analyte per air sample, respectively). Samples from private households and an office building were analyzed to explore differences in distribution patterns and concentrations. Perfluorooctane sulfonate, perfluorodecane sulfonate, perfluoroheptanoate, perfluorooctanoate and perfluorononanoate were observed in all samples of dust from private households, in the range from 1 to 80.1 ng g(-1). Fluorotelomer alcohols (FTOHs) were the predominant PFCs in indoor air samples with ∑FTOHs ranging between 4.7 and 17.9 ng m(-3). The concentrations found in the present study are generally lower than those previously reported. This variation may be due to differences associated with geographical locations and lifestyles. However, use of different sampling techniques and strategies among studies can introduce large variations in PFC concentration found, making direct comparisons challenging.

Biotransformation of the 8:2 fluorotelomer acrylate in rainbow trout. 1. In vivo dietary exposure

The bioaccumulation and biotransformation of the 8:2 fluorotelomer acrylate (C(8) F(17) CH(2) CH(2) OC(O)CH = CH(2) , 8:2 FTAc) was investigated in rainbow trout via dietary exposure. The 8:2 FTAc is a monomer used in the manufacture of fluorinated polymers and has been widely detected in the atmosphere. The parent 8:2 FTAc and suspected intermediate and terminal metabolites were monitored in liver, blood, kidney, bile, and feces during the 5-d uptake and 8-d elimination phases using gas chromatography-mass spectrometry (GC-MS)- and liquid chromatography-tandem mass spectrometry (LC-MS/MS)- based methods. Very low levels of the 8:2 FTAc were detected in the internal tissues and feces, suggesting that the 8:2 FTAc was rapidly biotransformed in the gut or liver. Similarly, low concentrations of the 8:2 fluorotelomer alcohol (FTOH) were accumulated in the fish tissues. The 8:2 saturated fluorotelomer carboxylate (FTCA) was formed in the highest concentration, reaching steady-state tissue concentrations of approximately 1,000 to 1,400 ng/g wet weight. The 8:2 FTUCA and 7:3 FTCA were also accumulated in high levels, at levels approximately 10-fold lower than the 8:2 FTCA. Both the 7:3 FTCA and perfluorooctanoate (PFOA) showed increasing levels throughout the uptake phase and into the initial stages of the elimination phase, indicating continued formation through precursors still present in the body. Perfluorononanoate (PFNA) was formed in low nanogram per gram wet weight levels. The intermediate and terminal metabolites were also detected in the bile and feces, indicating an important elimination pathway for these compounds. In addition, the 8:2 FTOH glucuronide conjugate was measured in relatively high concentrations in the bile and feces. The results of the current study demonstrated a scenario in which a biologically labile compound is biotransformed to terminal metabolites that are much more biologically persistent.

Indoor contamination with hexabromocyclododecanes, polybrominated diphenyl ethers, and perfluoroalkyl compounds: an important exposure pathway for people?

This review underlines the importance of indoor contamination as a pathway of human exposure to hexabromocyclododecanes (HBCDs), polybrominated diphenyl ethers (PBDEs), and perfluoroalkyl compounds (PFCs). There is ample evidence of substantial contamination of indoor dust with these chemicals and that their concentrations in indoor air exceed substantially those outdoors. Studies examining the relationship between body burden and exposure via indoor dust are inconsistent; while some indicate a link between body burdens and PBDE and HBCD exposure via dust ingestion, others find no correlation. Likewise, while concentrations in indoor dust and human tissues are both highly skewed, this does not necessarily imply causality. Evidence suggests exposure via dust ingestion is higher for toddlers than adults. Research priorities include identifying means of reducing indoor concentrations and indoor monitoring methods that provide the most "biologically-relevant" measures of exposure as well as monitoring a wider range of microenvironment categories. Other gaps include studies to improve understanding of the following: emission rates and mechanisms via which these contaminants migrate from products into indoor air and dust; relationships between indoor exposures and human body burdens; relevant physicochemical properties; the gastrointestinal uptake by humans of these chemicals from indoor dust; and human dust ingestion rates.

Partitioning of fluorotelomer alcohols (FTOH) to semipermeable membrane devices (SPMD)

BACKGROUND, AIM, AND SCOPE

Fluorotelomer alcohols (FTOH) are widely used substances that were detected even in remote regions of the world. For the determination of FTOH in the atmosphere, appropriate sampling techniques are needed. In this study, triolein-filled low-density polyethylene tubes were used as semipermeable membrane devices (SPMD) and tested for their suitability as passive air samplers for FTOH.

MATERIALS AND METHODS

Partitioning to and from SPMD were investigated for four FTOH of different chain length and concentration levels in laboratory and field experiments. FTOH were extracted by liquid-liquid extraction with acetonitrile:n-hexane 1:1 and determined by gas chromatography (GC)-positive ion chemical ionisation mass spectrometry (MS).

RESULTS

FTOH behaved differently depending on applied concentrations. At high FTOH levels, compound passage through the membrane and uptake appeared to be best for 6:2 FTOH, but passage of long-chain FTOH was in the same order of magnitude. At low FTOH concentration levels, mass transfer and uptake was best for short-chain FTOH. Partitioning of 4:2 FTOH to SPMD exceeded partitioning of 10:2 FTOH by nearly two orders of magnitude.

DISCUSSION

FTOH partitioning to SPMD seems to be dependent on the fluorinated chain length and controlled by the SPMD membrane acting as a barrier. Migration of long-chain FTOH through the membrane was hampered, probably due to the oleophobic properties of the fluorinated alkyl chain. Because of the constricted diffusion of FTOH through the SPMD membrane at low FTOH levels, an adequate accumulation in the passive sampler is prevented. Thus, sensitivity of the analytical method in combination with the enrichment of FTOH in SPMD was not sufficient to achieve adequate method detection limit at low FTOH levels.

CONCLUSIONS

Application of SPMD as passive air samplers for FTOH did not seem to be a suitable method for environmentally relevant FTOH concentrations.

RECOMMENDATIONS AND PERSPECTIVES

As a consequence, we can only recommend the use of SPMD for FTOH of presumably high contamination levels.

Atmospheric perfluorinated acid precursors: chemistry, occurrence, and impacts

Perfluorocarboxylic acids (PFCAs) can be found from the hydrolysis of perfluoroacyl fluorides and chlorides, which can be produced in three separate ways in the atmosphere. Alternatively, PFCAs can be formed directly in the gas phase through reaction of perfluoroacyl peroxy radicals or perfluorinated aldehyde hydrates. All five mechanisms have been elucidated using smog chamber techniques. Yields of the PFCAs from this process vary from less than 10% to greater than 100%, depending on the mechanism. The formation of perfluorosulfonic acids in the atmosphere can also occur, though the mechanism has not been entirely elucidated. A large number of compounds have been confirmed as perfluorinated acid precursors, including CFC-replacement compounds, anesthetics, fluorotelomer compounds, and perfluorosulfonamides. Levels of some of these compounds have been measured in the atmosphere, but concentration for the majority have yet to be detected. It is clear that atmospheric oxidation of volatile precursors contributes to the overall burden of PFAs, though the extent to which this occurs is compound and environment dependent and is difficult to assess accurately.

Modeling the hydrolysis of perfluorinated compounds containing carboxylic and phosphoric acid ester functions and sulfonamide groups

Temperature-dependent rate constants were estimated for the acid- and base-catalyzed and neutral hydrolysis reactions of perfluorinated telomer acrylates (FTAcrs) and phosphate esters (FTPEs), and the S(N)1 and S(N)2 hydrolysis reactions of fluorotelomer iodides (FTIs). Under some environmental conditions, hydrolysis of monomeric FTAcrs could be rapid (half-lives of several years in marine systems and as low as several days in some landfills) and represent a dominant portion of their overall degradation. Abiotic hydrolysis of monomeric FTAcrs may be a significant contributor to current environmental loadings of fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylic acids (PFCAs). Polymeric FTAcrs are expected to be hydrolyzed more slowly, with estimated half-lives in soil and natural waters ranging between several centuries to several millenia absent additional surface area limitations on reactivity. Poor agreement was found between the limited experimental data on FTPE hydrolysis and computational estimates, requiring more detailed experimental data before any further modeling can occur on these compounds or their perfluoroalkyl sulfonamidoethanol phosphate ester (PFSamPE) analogs. FTIs are expected to have hydrolytic half-lives of about 130 days in most natural waters, suggesting they may be contributing to substantial FTOH and PFCA inputs in aquatic systems. Perfluoroalkyl sulfonamides (PFSams) appear unlikely to undergo abiotic hydrolysis at the S-N, C-S, or N-C linkages under environmentally relevant conditions, although potentially facile S-N hydrolysis via intramolecular catalysis by ethanol and acetic acid amide substituents warrants further investigation.

Modeling the global fate and transport of perfluorooctane sulfonate (PFOS) and precursor compounds in relation to temporal trends in wildlife exposure

A global-scale fate and transport model was applied to investigate the historic and future trends in ambient concentrations of perfluorooctane sulfonate (PFOS) and volatile perfluorooctane sulfonyl fluoride (POSF)-based precursor compounds in the environment. First, a global emission inventory for PFOS and its precursor compounds was estimated for the period 1957-2010. We used this inventory as input to a global-scale contaminant fate model and compared modeled concentrations with field data. The main focus of the simulations was to examine how modeled concentrations of PFOS and volatile precursor compounds respond to the major production phase-out that occurred in 2000-2002. Modeled concentrations of PFOS in surface ocean waters are generally within a factor of 5 of field data and are dominated by direct emissions of this substance. In contrast, modeled concentrations of the precursor compounds considered in this study are lower than measured concentrations both before and after the production phase-out. Modeled surface ocean water concentrations of PFOS in source regions decline slowly in response to the production phase-out while concentrations in remote regions continue to increase until 2030. In contrast, modeled concentrations of precursor compounds in both the atmosphere and surface ocean water compartment in all regions respond rapidly to the production phase-out (i.e., decline quickly to much lower levels). With respect to wildlife biomonitoring data, since precursor compounds are bioavailable and degrade to PFOS in vivo, it is at least plausible that declining trends in PFOS body burdens observed in some marine organisms are attributable to this exposure pathway. The continued increases in PFOS body burdens observed in marine organisms inhabiting other regions may reflect exposure primarily to PFOS itself, present in the environment due to production and use of this compound as well as degradation of precursor compounds.

Polyfluorinated compounds in the atmosphere of the Atlantic and Southern Oceans: evidence for a global distribution

High volume air samples taken onboard several research vessels in the Atlantic Ocean, the Southern Ocean, and the Baltic Sea as well as at one land-based site close to Hamburg, Germany, in 2007 and 2008 were analyzed for per- and polyfluorinated organic compounds (PFCs). A set of neutral, volatile PFCs such as fluorotelomer alcohols (FTOH) or perfluoroalkyl sulfonamides and ionic nonvolatile PFCs like perfluorinated carboxylates (PFCA) and sulfonates (PFSA) were collected on PUF/XAD-2/PUF cartridges and glass fiber filters and determined using GC-MS and HPLC-MS/MS. PFCs were detected in all air samples, even in Antarctic regions, and occurred predominantly in the gas phase. Total gas-phase concentrations of ship-based samples ranged from 4.5 pg m(-3) in the Southern Ocean to 335 pg m(-3) in European source regions. Concentrations of 8:2 FTOH, the analyte that was usually observed in highest concentrations, were between 1.8 and 130 pg m(-3). PFC concentrations decreased from continental regions toward marine regions and from Central Europe toward the Arctic and Antarctica. Southern hemispheric concentrations of individual PFCs were significantly lower than those of the northern hemisphere. On the basis of this data set, marine background PFC concentrations and atmospheric residence times were calculated. This study gives further evidence that volatile PFCs undergo atmospheric long-range transportto remote regions and may contribute to their contamination with persistent PFCA and PFSA.

Annual time series of air concentrations of polyfluorinated compounds

Per- and polyfluorinated organic compounds (PFC) in air were determined in samples taken at two sites in the vicinity of Hamburg, Germany, over a period of 14 months. PUF/XAD-2/PUF cartridges and glass fiber filters were applied for the collection of airborne PFC. A set of volatile, neutral PFCs such as fluorotelomer alcohols (FTOH) or perfluorinated sulfonamides and ionic, nonvolatile PFC like perfluorinated carboxylates and sulfonates were determined using GC-MS and HPLC-MS/MS. Backward trajectory analysis was performed to elucidate the origin of the air mass parcels sampled. PFCs were predominantly detected in the gas phase. A fluctuating baseline presenting north German background levels and singular events of high concentrations were characteristic for the time series of all analytes and both locations. The origin of sampled air was the driving parameter influencing the PFC levels. Elevated PFC concentrations occurred in air arriving from industrialized and populated regions west and southwest of Hamburg. Maximum individual PFC concentrations reached 600 pg m(-3) (8:2 FTOH) in the gas phase and 13 pg m(-3) (perfluorooctane sulfonate) in the particle phase. The class of FTOH clearly dominated the gas-phase substance spectrum. The compound that was detected in highest concentrations was 8:2 FTOH. Individual gas-phase PFC concentrations were higher in summer than in winter. Temperature-dependent emissions of volatile and semi-volatile PFCs from diffuse sources to the gas phase are presumed to be responsible for this observation.

Atmospheric chemistry of 4:2 fluorotelomer acrylate [C4F9CH2CH2OC(O)CH=CH2]: kinetics, mechanisms, and products of chlorine-atom- and OH-radical-initiated oxidation

Relative rate techniques were used to measure the rate constants k[Cl + C(4)F(9)CH(2)CH(2)OC(O)CH=CH(2)] = (2.21 +/- 0.16) x 10(-10) and k[OH + C(4)F(9)CH(2)CH(2)OC(O)CH=CH(2)] = (1.13 +/- 0.12) x 10(-11) cm(3) molecule(-1) s(-1) in 700 Torr of N(2) or air diluent at 296 K. The atmospheric lifetime of C(4)F(9)CH(2)CH(2)OC(O)CHCH(2) (4:2 FTAc) is determined by its reaction with OH radicals and is approximately 1 day. The chlorine-atom-initiated oxidation of 4:2 FTAc in 700 Torr of air at 296 K gives C(4)F(9)CH(2)C(O)H in molar yields of 18% and 10% in the absence and presence of NO, respectively. The OH-radical-initiated oxidation of 4:2 FTAc in 700 Torr of air in the presence of NO gives HCHO in a molar yield of (102 +/- 7)%, with C(4)F(9)CH(2)CH(2)OC(O)C(O)H (4:2 fluorotelomer glyoxylate) as the expected coproduct. The atmospheric fate of the 4:2 fluorotelomer glyoxylate will be photolysis and reaction with OH radicals, which will lead to the formation of C(4)F(9)CH(2)C(O)H and ultimately perfluorinated carboxylic acids. The atmospheric oxidation of fluorotelomer acrylates is a potential source of perfluorinated carboxylic acids in remote locations.

Current levels of airborne polyfluorinated telomers in Japan

Fluorotelomer alcohols (FTOHs), a class of per- and poly-fluorochemicals (PFCs), are environmental contaminants characterized by high volatility and are therefore prone to long-range atmospheric transport. In this study, airborne FTOHs were identified in Japan using a newly developed passive air sampler containing activated carbon felts. Air sampling was conducted at 33 sites all over Japan from April to June 2007. 8:2 FTOH, the dominant analyte, ranged from <32 to 2466pgm(-3) (mean: 241pgm(-3)) followed by 6:2 FTOH from n.d. to 768pgm(-3) (mean: 51.6pgm(-3)), 10:2 FTOH from <17 to 113pgm(-3) (mean: 26.8pgm(-3)) and 8:2 FTOAcryl from n.d. to 480pgm(-3) (mean: 25.8pgm(-3)). 8:2 FTOMethacryl was not detected above detection limit (3pgm(-3)) in all samples. The highest concentration of total investigated PFCs was found in Chiba (35 degrees 43'20'' N 140 degrees 39'46'' E) (2152-3181pgm(-3)). On the other hand, in three locations of Higashi-Yodogawa (34 degrees 44' N 135 degrees 32' E), high levels of 8:2 FTOAcryl (239pgm(-3), 109-480pgm(-3)) were detected, the levels of which were comparable to those of 8:2 FTOH (mean: 175pgm(-3), range: 115-292pgm(-3)). This study is the first national wide-scale survey of FTOHs and 8:2 FTOAcryl across Japan, showing that 8:2 FTOH was ubiquitous in the environment in Japan.