Bubble preconcentration coupled with SALDI-TOF MS for rapid detection of PFAS in environmental water

Per- and polyfluoroalkyl substances (PFASs) are highly persistent and bioaccumulative contaminants that pose serious ecological and human health risks even at trace levels. In this study, we developed a rapid and eco-friendly bubble preconcentration–surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) method for PFAS detection in water. Compared with our previous design, the average bubble size was reduced from 312 to 243 μm, enhancing the enrichment of short-chain PFASs. Using an iron-based metal–organic framework (MIL-101(Fe)) as the assisting material, the method achieved enrichment ratios of 700-fold for PFOS and 400-fold for PFHxS within 30 s. The entire analysis is completed within minutes without organic solvents, offering substantial reductions in time and waste compared with conventional SPE–LC–MS/MS. PFOS concentration of ~3 ng/L was detected in Tamsui River samples, consistent with LC–MS/MS results. This solvent-free, small-bubble-based method provides a sustainable approach for rapid PFAS monitoring in environmental waters.