Rapid, Efficient, and Green Analytical Technique for Determination of Fluorotelomer Alcohol in Water by Stir Bar Sorptive Extraction

Abstract

Fluorotelomer alcohols (FTOHs) are one of the major classes of Per- and polyfluoroalkyl substances (PFAS). While some common PFAS are voluntarily phased out due to their potential toxicity, persistence, and ubiquitous presence in the environment, FTOHs are precursors of perfluorocarboxylic acids (PFCAs), which are used as alternatives to conventional PFAS. Consequently, FTOHs are commonly detected in water matrices, which eventually indicate PFAS contamination in drinking water supplies and thus a potential source of human exposure. Even though studies have been conducted nationwide to evaluate the degree of FTOHs in the water environment, robust monitoring is lacking due to the unavailability of simple and sustainable analytical extraction and detection methods. To fill the gap, we developed and validated a simple, rapid, minimal solvent, no clean-up, and sensitive method for the determination of FTOHs in water by stir bar sorptive extraction (SBSE) coupled with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Three commonly detected FTOHs (6:2 FTOH, 8:2 FTOH, and 10:2 FTOH) were selected as the model compounds. Factors such as extraction time, stirring speed, solvent composition, salt addition, and pH were investigated to achieve optimal extraction efficiency. This "green chemistry" based extraction provided good sensitivity and precision with low method limits of detection ranging from 2.16 ng/L to 16.7 ng/L and with an extraction recovery ranging 55% to 111%. We applied our developed method for the simultaneous determination of the FTOHs in tap water, brackish water, and wastewater influent and effluent. 6:2 FTOH and 8:2 FTOH were detected in two wastewater samples at 78.0 and 34.8 ng/L, respectively. This optimized SBSE-TD-GC-MS method will be a valuable alternative to investigate FTOHs in water matrices.

Keywords: Per- and polyfluoroalkyl substances (PFAS), Fluorotelomer alcohol (FTOH), Stir bar sorptive extraction (SBSE), Method Development, GC-MS, wastewater