Environ. Sci. Technol. 2004, 38, 991-996
Polyfluorinated Telomer Alcohols and Sulfonamides in the North American Troposphere NAOMI L. STOCK,† FIONA K. LAU,† DAVID A. ELLIS,† JONATHAN W. MARTIN,† DEREK C. G. MUIR,‡ AND S C O T T A . M A B U R Y * ,† Department of Chemistry, University of Toronto, 80 St. George Street, Toronto Ontario M5S 3H6, Canada, and National Water Institute, Environment Canada, Burlington, Ontario L7R 4A6, Canada
In 2001, a sampling campaign was conducted in six North American citiessReno, NV; Griffin, GA; Cleves, OH; Winnipeg, MB; Long Point, ON; and Toronto, ONsto investigate the tropospheric distribution of a suite of polyfluorinated alcohols and amides. Analysis via gas chromatography-chemical ionization-mass spectrometry indicated that both polyfluorinated sulfonamides and fluorinated telomer alcohols (FTOHs) are widely distributed throughout the North American troposphere with mean concentrations ranging from 22 to 403 pg/m3 and from 11 to 165 pg/m3 respectively. The dominant polyfluorinated contaminant was dependent on sampling location. Large mean concentrations of N-methyl perfluorooctane sulfonamidoethanol (359 pg/m3) and N-ethyl perfluorooctane sulfonamidoethanol (199 pg/m3) identified in Griffin and Reno, respectively, may indicate the release of polyfluorinated sulfonamides to the environment through paper and carpet treatment processes. The nonuniform nature of the spatial distribution of both polyfluorinated sulfonamides and FTOHs is indicative of the importance of point sources for the dissemination of these contaminants in the North American troposphere.
Introduction Perfluorooctane sulfonate (PFOS) (C8F17SO3-) has recently emerged as a priority environmental pollutant due to its widespread detection in biotasincluding both Arctic and Antarctic species (1, 2)sand its persistent and bioaccumulative nature (3). As the calculated Henry’s law value for PFOS is 4.7 × 10-9 atm‚m3/mol (4), it is unlikely to enter into the atmosphere directly and undergo global dissemination. As such, it has been hypothesized that PFOS must be globally distributed via more volatile, neutral airborne contaminants that undergo long-range transport to remote areas and degrade to yield the free acid (4-6). The mechanisms by which these neutral contaminants enter the environment may include release during manufacturing and application processes, leaching from both consumer products and waste products in landfills due to abiotic and/or biotic degradation processes, and/or the release of residual materials in the * Corresponding author phone: (416)978-1780; fax: (416)978-3596; e-mail:
[email protected]. † University of Toronto. ‡ Environment Canada. 10.1021/es034644t CCC: $27.50 Published on Web 01/08/2004
2004 American Chemical Society
final products (7). Similarly, perfluoroalkyl carboxylates (PFCAs) (CF3(CF2)nCOO-; where n equals 6-13) have recently been observed in biota (2, 8, 9). Currently the only known source of PFCAs to the environment is the thermolyis of fluoropolymers (10); other possible sources include the degradation of polyfluorinated alcohols. The polyfluorinated sulfonamides, produced electrochemically by the 3M Company, are expected to degrade to PFOS during both abiotic and biological degradation processes (7). Polyfluorinated sulfonamides are used in a variety of products including surface treatments (for fabric, leather, upholstery, and carpet), paper protectors, and performance chemicalsssuch as fire-fighting foams, mining surfactants, alkaline cleaners, floor polishes, photographic film, denture cleaners, chemical intermediates, shampoos, carpet spot cleaners, and insecticides (4). Recently, the 3M Company, a major manufacturer of polyfluorinated sulfonamides, announced that it would discontinue the production of all perfluorooctyl chemicals (including PFOS and polyfluorooctyl sulfonamides) by 2003. In 2000, the annual production of all PFOS-related chemicals in the United States was 3 million kg (4). Fluorinated telomer alcohols (FTOHs), so named due to their production via the telomerization process, are a class of linear, long-chain, polyfluorinated alcohols; individual FTOHs are named based on the ratio of fluorinated carbons to hydrogenated carbons in the molecule (Table 1). FTOHs are currently produced and used as intermediates for the synthesis of inks, paints and coatings, polymers, adhesives, waxes and polishes, and caulks (11). The global production of FTOHs in 2000-2002 was estimated at 5-6.5 million kg/yr, of which 40% was produced in North America (12). FTOHs and polyfluorinated sulfonamides have previously been measured in the environment. Martin et al. (5) discovered the tropospheric presence of six polyfluorinated alcohols and amidessthe 6:2, 8:2, and 10:2 FTOHs, N-ethyl perfluorooctane sulfonamide (NEtFOSA), N-methyl perfluorooctane sulfonamidoethanol (NMeFOSE), and N-ethyl perfluorooctane sulfonamidoethanol (NEtFOSE) (Table 1). FTOHs and polyfluorinated sulfonamides in the troposphere were observed at concentrations ranging from 7 to 196 pg/m3 and from 14 to 393 pg/m3, respectively. Higher concentrations of both polyfluorinated alcohols and amides were observed in the urban location relative to the rural location. The goal of this investigation was to determine the spatial distribution of a suite of polyfluorinated alcohols and amides in the North American troposphere. Samples were collected in six locations and analyzed by gas chromatographychemical ionization-mass spectrometry. Sampling locations were selected as either rural locations or for the nearby presence of industrial sources. Possible point sources of polyfluorinated alcohols and amides were identified, and geographical trends were described.
Experimental Section Chemicals, Standards, and Sampling Media. Optima grade methanol and ethyl acetate (both 99.9%) were obtained from Fisher Scientific (Toronto, ON). The 6:2, 8:2, and 10:2 FTOH standards (all 97%) were purchased from Oakwood Research Chemicals (West Columbia, SC). NMeFOSE (96.32%) and NEtFOSE (97%) standards were donated by 3M Company (St. Paul, MN). NEtFOSA (95%) and nonadecafluoro-1decanol (NDFD) (98%) standards were purchased from Lancaster Synthesis (Pelham, NH) and Aldrich Chemical Co. (Milwaukee, WI), respectively. All solvents and standards were used as received. Amberlite XAD-2 resin was obtained from VOL. 38, NO. 4, 2004 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 1. Analytes of Interest: Acronyms, Structures, and Ions Monitored in Positive Chemical Ionization (PCI) Modea
a
An asterisk (*) indicated detection of analyte confirmed in negative chemical ionization (NCl) mode (m/z ) 526).
Supelco (Oakville, ON). Polyurethane foam (PUF) slices (2.5 cm) and quartz fiber filters (10.16 cm in diameter, Whatman QMA) were purchased from Tisch Environmental Inc. (Cleves, OH). All sampling media were prepared prior to sampling as discussed below. High-purity nitrogen was obtained from BOC Gases (Whitby, ON). Sampling Media Preparation. To minimize contamination, all handling of sampling media was conducted under clean laboratory conditions (positive pressure, carbon- and HEPA-filtered air) at the National Water Research Institute (Burlington, ON). Preparation of the XAD resin and PUF slices consisted of a 2-day Soxhlet extraction with methanol followed by a 2-day Soxhlet extraction with ethyl acetate. The wet XAD resin and PUF slices were then dried under a flow of high-purity nitrogen. Quartz fiber filters were baked overnight at 500 °C, rinsed several times with ethyl acetate in a Buchner funnel, dried under high-purity nitrogen, and individually wrapped in aluminum foil (baked overnight at 500 °C). Quartz fiber filters and glass cartridges, packed with 25 g of XAD sandwiched between two PUF slices, were sealed in double polyethylene bags for transport to the sampling locations. Sampling Campaign. Sampling supplies were delivered by courier to five sampling sites across North AmericasReno, NV; Griffin, GA; Cleves, OH; Winnipeg, MB; and Long Point, ON. Sampling was also conducted near our laboratory in downtown Toronto, ON, for a total of six sampling locations (Figure 1). Each sampling site was equipped with a conventional high-volume air sampler, modified by removing all fluorinated polymer materials. Particulate phase was collected on the quartz fiber filters, while gaseous phase was trapped in the XAD-PUF sandwich. Air samplers were operated with flow rates of 0.2-0.4 m3/min. Samples were typically collected for 96 h (495-1574 m3) (Table 2). At each sampling location, three air samples and a field blank were obtained. An attempt was made to sample at all six locations concurrently (Table 2); the notable exception was sample 1 992
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at the Toronto location due to power failure. Two additional samples, collected immediately after the sampling campaign, were obtained at the Griffin location. Throughout the sampling period, ambient pressure and temperature data were collected at each location. At the completion of the sampling campaign, samples were returned in sealed bags, via courier, to our laboratory for extraction and analysis. All samples were transported at ambient temperatures. It is possible that some volatilization of target analytes did occur, and as such, concentrations reported in this study may be lower than actual tropospheric concentrations. Upon return to our laboratory, samples were stored at 4 °C prior to extraction and analysis. Sample Extraction and Instrumental Analysis. No attempt was made in this study to distinguish between gasphase and particle-bound concentrations. As such, the quartz fiber filter, XAD, and PUFs of each sample were combined in a clean, custom glass column containing approximately 200 mL of methanol and allowed to soak for 1 h. The methanol was eluted and replaced with approximately 200 mL of ethyl acetate and allowed to soak for 30 min prior to elution. The 30-min ethyl acetate soak was repeated three times. The eluting methanol and ethyl acetate were passed thorough sodium sulfate and combined. Following elution, the internal standard nonadecafluoro-1-dodecanol (NDFD) was added to each sample. Samples were subsequently rotoevaporated to approximately 10 mL, filtered through 0.2 µm nylon syringe filters (Acrodisc, Pall Gelman), and concentrated to 200 µL under a gentle flow of high-purity nitrogen. Analysis of target analytessthree FTOHs (6:2, 8:2, and 10:2) and three polyfluorinated sulfonamides (NEtFOSA, NEtFOSE, and NMeFOSE) (Table 1)swas conducted according to the method of Martin et al. (5). Briefly, analytes were detected using gas chromatography-mass spectrometry (GC-MS) employing chemical ionization (CI) and operating in selected ion monitoring (SIM) mode. Two fragments were monitored for each analyte in positive CI (Table 1), with the
FIGURE 1. Map of North America illustrating the six sampling locations. The primary location of carpet production and treatment facilities is indicated by large shaded circle.
TABLE 2. Sample Locations, Populations, Sampling Dates, Mean Temperatures, Sample Volumes, and Total Concentrations of Polyfluorinated Sulfonamides and FTOHs (pg/m3) sample no.
sampling dates (2001)
mean temp (°C)
vol sampled (m3)
concn of total polyfluorinated sulfonamides (pg/m3)b
concn of total FTOHs (pg/m3)b
1 2 3 4 5
Nov 2-5 Nov 5-8 Nov 12-15 Nov 16-19 Nov 26-29
2 200c
1 2 3
Nov 2-5 Nov 6-12 Nov 12-15
500
1 2 3
Nov 2-5 Nov 5-8 Nov 12-15
2 480 000
1 2 3
Nov 20-23 Nov 6-9 Nov 12-15
Reno, NV
180 500
1 2 3
Nov 2-5 Nov 6-12 Nov 12-16
Winnipeg, MB
685 900
1 2 3
Nov 2-5 Nov 5-8 Nov 12-15
16.6 12.8 12.2 13.3 17.9 (14.6) 11.0 7.4 7.5 (8.6) 9.5 11.4 10.0 (10.3) 7.1 9.0 10.6 (8.9) 11.7 9.1 8.0 (9.6) 3.6 2.9 46 (3.7)
746 732 737 757 737 (742) 881 894 864 (881) 856 828 857 (847) 650 649 656 (652) 495 916 653 (688) 1549 1574 1561 (1561)
188 90 57 129 1549 (403)
