Vial-coated thin film microextraction for perfluoroalkyl carboxylic acids (PFCAs) determination in water by GC–MS

Abstract

Perfluoroalkyl carboxylic acids (PFCAs), a subclass of perfluoroalkyl substances (PFAs) commonly detected in water, are of increasing concern due to their persistence, bioaccumulative nature, and harmful effects on health. Determining PFCAs in environmental matrices is challenging because they are typically present at ng L⁻¹ levels and tend to adsorb onto materials like filtration membranes, causing significant losses during analysis. To address these challenges, a thin-film microextraction (TFME)-coated vial was designed for PFCA (C5–C10) extraction, coupled with gas chromatography-mass spectrometry (GC–MS). Glass was selected as the support material due to its low adsorption rate and superior chemical resistance compared to other polymers. The TFME coating, made from a weak anion exchange resin and polyacrylonitrile (10 % w/w) as a binder polymer, effectively extracts analytes from complex matrices while minimizing co-extraction of interfering macromolecules. The method eliminates the need for sample filtration, preventing PFCA loss in filtration membranes. Under optimal conditions, the extraction efficiency ranged from 70 to 100 %. Detection and quantification limits were 0.13–2.1 ng L⁻¹ and 0.42–7.1 ng L⁻¹, respectively. Intra- and inter-assay relative standard deviations (% RSD) were 4.9–2.2 % and 4.8–2.3 %, respectively, with a linear working range of 10–1000 ng L⁻¹ for the TFME-coated device. This method is suitable for PFCA determination in drinking water and complies with the Directive 2020/2184, which sets a maximum allowable limit of 500 ng L⁻¹ for total PFAs.