A Comprehensive, Simple, Robust, and Solvent-Free Method Covering Ultrashort- to Long-Chain PFAS in Atmospheric Samples

Ultrashort- and short-chain perfluoroalkyl and polyfluoroalkyl substances (PFAS), including trifluoroacetic acid (TFA), are emerging as widespread and persistent atmospheric pollutants of growing concern. Their atmospheric accumulation is further exacerbated by the transformation from various precursors, such as long-chain perfluorocarboxylic acids (PFCAs) and neutral PFAS. An efficient analytical method covering ultrashort- to long-chain PFAS is therefore required to monitor environmental levels and understand transformation mechanisms. However, distinct polarity among these PFAS poses technical challenges for simultaneous detection within a single run, hindering the comprehensive understanding of degradation mechanisms and quantitative correlation analysis. Conventional methods using liquid chromatography-electrospray ionization (LC-ESI) are effective for medium- to long-chain PFAS but are limited in detecting ultrashort-chain species concurrently. Herein, we present a simple yet robust method for broad-spectrum PFAS analysis, covering ultrashort- to long-chain species, using dielectric barrier discharge ionization (DBDI) coupled directly to high-resolution tandem mass spectrometry (HRMS/MS). This approach enables efficient ionization across a wide polarity range with reduced intensity of in-source fragmentation (ISF). Moreover, solid-phase microextraction (SPME) simplifies labor- and time-intensive sample preparation without solvents. As a result, a high sensitivity of 0.06-2.02 pg/m³ was achieved with minimal background interference, and ISF was reduced by over 60% compared to existing methods. Using this approach, we explored potential environmental associations between PFAS and cooccurring pollutants in seasonal atmospheric samples, showcasing its utility for future environmental research.