Per- and polyfluoroalkyl substances (PFAS) are chemical compounds that have been used in numerous industries, commercial applications, and extensively in aqueous film-forming foams for fire-fighting activities. They are environmentally persistent compounds and reported to cause adverse effects on human health. Recently, EPA published a draft method 1633 that requires aqueous, solids, biosolids and tissue samples to store at freezing temperature ≤ - 20°C until sample preparation.<br/>To evaluate the storing condition of EPA draft method, this study aimed to assess the stability of 70 PFAS (perfluoroalkyl acids (PFAAs) and precursors) in effluent wastewater (WW) and lab-water (LW) at different sample storage temperature and pH. We hypothesize that the microbial activities in effluent WW stored (short term for 35 days) at refrigeration temperature and acidic conditions are inhibited/insignificant, which stops interconversion of precursors or oxidation of precursors into PFAAs. PFAS (25–40 ng/mL) were spiked in both samples and stored at room (20°C), refrigeration (4°C), freezing (-20°C) temperature, and sample with adjusted pH of 2-3 for 35 days. These PFAS include C3 through C16 perfluorocarboxylic acids (PFCAs); C4 through C12 perfluoro sulfonates (PFSAs), and precursors that include n:2 (4:2, 6:2, 8:2 and 10:2) sulfonates; fluorotelomere carboxylates (3:3, 5:3, 6:2, 7:3, and 8:2 FTCAs); FTUCAs (6:2 and 8:2); perfluorooctane sulfonamides (PFOSA, N-MeFOSA, and N-EtFOSA); perfluorooctane sulfonamide ethanols (N-MeFOSE and N-EtFOSE); and perfluorooctane sulfonamide acetic acids (N-MeFOSAA and EtFOSAA) among others. Analyzed data were quantified to determine if recovery was between 70 and 130% and change of PFAS concentrations in the samples were statistically determined within the recovery range.<br/>Preliminary measurements of PFAAs and precursors showed no significant (p = 0.05) change in concentrations over initial one week time in the different storage conditions investigated. This study would provide a baseline information about short-term sample storage temperature and pH that applicable to commercial testing laboratories.

Effect of sample storage conditions on the quantification and determination of 70 PFAS: Do precursor concentrations change during storage?

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.