Measuring short-chain per- and polyfluoroalkyl substances in Central New Jersey air using chemical ionization mass spectrometry

Figures & data

Figure 1. Photos from the field site. (a) The instrument trailer located on a grassy field at the EPA/ORD/CESER facility in Edison, NJ. (b) A view of the air sampling inlet extending from the ceiling of the trailer. (c) A view of the inlet delivering sampled ambient air to the iodide CIMS instrument inside the trailer.

Table 1. Iodide CIMS sensitivities and LODs for PFCAs and FTOHs.

Compound	Sensitivity (Hz pptv^−1)	LOD (pptv)	LOD (ng m^−3)^a
TFA	30 ± 10	0.4	20
PFPrA	60 ± 10	0.7	50
PFBA	30 ± 10	0.3	30
PFPeA	30 ± 10	0.2	20
PFHxA	30 ± 80	N/A	N/A
4:2 FTOH	2.0 ± 0.1	2.9	320
6:2 FTOH	4.1 ± 0.1	1.6	240

Notes. ^aCalculated at standard temperature and pressure.

Figure 2. Time series of TFA mixing ratios (top panel) and estimated mixing ratios of C₃H₂F₆O (middle panel) and C₆HF₁₁O₃ (bottom panel). Mixing ratios are in units of parts-per-trillion by volume (pptv).

Figure 3. Diel profiles of TFA mixing ratios (top panel), estimated C₃H₂F₆O mixing ratios (middle panel), relative CIMS signals for C₅H₁₀O₃ (bottom panel; left axis), and air temperature near the field site (bottom panel; right axis). C₅H₁₀O₃ likely represents a sum of isoprene hydroxyhydroperoxides (ISOPOOH) and epoxydiols (IEPOX), which are tracers for near-surface secondary photochemical production (Paulot et al. 2009). Shaded area represents ± one standard deviation of binned (averaged) mixing ratio data. Binned averages of TFA mixing ratios include data below instrumental LOD, and thus may not be reliable. Air temperature data are from the Rutgers PAM meteorological station (http://pamsite.rutgers.edu/).

Figure 4. Estimated C₆HF₁₁O₃ mixing ratios (top panel) and wind speed and direction (bottom panel) between 13:30 on 8/2/2023 and 06:00 on 8/3/2023. Wind direction data are reported in units of degrees, with 0° representing northerly winds, 90° representing easterly winds, 180° representing southerly winds, and 270° representing westerly winds. Wind speed and direction data are from the Rutgers PAM meteorological station (http://pamsite.rutgers.edu/).

Paulot, F., J. D. Crounse, H. G. Kjaergaard, A. Kürten, J. M. St. Clair, J. H. Seinfeld, and P. O. Wennberg. 2009. Unexpected epoxide formation in the gas-phase photooxidation of isoprene. Science 325 (5941):730–33. doi:10.1126/science.1172910.

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Data availability statement

The data that support the findings of this study are openly available at https://doi.org/10.23719/1530551.