Perfluoroalkyl carboxylic acids (PFCAs), a subcategory of poly- or perfluoroalkyl substances (PFAS), have become chemicals of environmental concern because many have the characteristics of persistent organic pollutants; toxicity, stability and persistence in the environment, high mobility, and bioaccumulation. PFCAs are extremely persistent and ubiquitous in environmental matrices, as well as in wildlife and humans, worldwide. PFCAs and their precursors can undergo long-range atmospheric transport leading to their worldwide distribution through wet and dry deposition.

Our custom-built passive air samplers (PAS) contain an overlying polypropylene filter which blocks particles and allows gases to permeate through to a nylon filter onto which gas phase acids, including PFCAs, selectively sorb. Each PAS is enclosed inside a weatherproof cap which protects it from wind, precipitation, and sunlight, while allowing continuous diffusion of acids to the nylon filter. Our PAS are capable of sampling gas-phase PFCAs, offering a simple, low-cost alternative to active samplers, meaning that the PAS can be deployed virtually anywhere due to their power-free and low maintenance design. Demonstration of the capabilities of these PAS will enable more widespread research on contamination levels and long-range transport processes of PFCAs. Such research is essential for a comprehensive understanding of the risks PFCAs pose to the environment and human health.

The objectives of this research are selection of internal standards for quantitative method optimization at ultra-trace levels, and ambient monitoring of short chain (C2-C6) PFCAs in the atmosphere with passive air samplers, using Ion Chromatography-Mass Spectrometry for analysis.

One preliminary finding related to internal standards is that in the absence of a 13C-PFPrA internal standard (IS), the 13C-TFA IS should be used to normalize PFPrA peaks, as the PFPrA recoveries using the 13C-PFBA internal standard were not equivalent to those using the 13C-PFPrA IS.

Triplicate passive air samplers (PAS) were deployed at four Toronto locations to obtain ultra trace data (ppqv to pptv-levels) on the atmospheric concentrations of C2-C6 PFCAs. Measurements were obtained from three locations as part of the Study of Winter Air Pollution in Toronto (SWAPIT) campaign, and at Pearson International Airport, a suspected hotspot. PAS from the SWAPIT sampling sites showed similar ppqv-level PFCA concentrations, with mixing ratios for the shortest chain PFCAs (TFA and PFPrA) 6 to 9 times higher than PFBA. These observations provide further insight on the abundance, sources, transport, and deposition of PFCAs in an urban megacity, where use and release of precursors is substantial.

¹ Department of Chemistry, York University, Toronto, ON, Canada

² Environment and Climate Change Canada, Downsview, ON, Canada

* Corresponding Author: inisto94@yorku.ca