Micro(nano)plastic interference on the solid‑phase extraction quantification of per‑ and polyfluoroalkyl substances...

Micro(nano)plastics (MNPs) are ubiquitous in aquatic environments and can act as vectors for per- and polyfluoroalkyl substances (PFAS). However, the extent to which MNP-PFAS interactions influence the analytical recovery of PFAS over time remains unclear. In this study, we investigated the impact of polystyrene particles (100 nm and 3 μm) on the recovery of 22 PFAS across four classes from water over 1, 7 and 28 days. The results revealed that MNPs introduce time-dependent and compound specific biases in PFAS recovery. For perfluorinated carboxylic acids (PFCAs) and sulfonic acids (PFSAs), recoveries were initially enhanced on Day 1 (76.6%-122% vs. control 58.7%-98.6%) and Day 7 (86.3%-127% vs. control 84.5%-121%), followed by a decline to levels comparable to or slightly below controls on Day 28 (55.8%-127% vs. control 56.4%-127%). Nanoplastics (NPs) induced greater enhancement than microplastics for PFCAs, whereas both particle sizes exhibited comparable effects for PFSAs. Perfluorooctane sulfonamide derivatives and fluorotelomer sulfonic acids showed a distinct pattern of an initial enhancement on Day 1 followed by a rapid return to control levels on Day 7. These temporal patterns indicate an evolution from weak, reversible adsorption to stronger binding over time, which may lead to overestimation of PFAS concentrations at early exposure stage and underestimation after prolonged contact. Molecular mechanics calculations provided a preliminary molecular-level rationale for the observed compound-specific differences, with a significant correlation between the adsorption energy and NP-induced recovery enhancement for 20 neutral PFAS (ρ = -0.58, p = 0.007), although they reflect intrinsic adsorption affinities on a model surface in vacuum rather than absolute aqueous-phase values. These findings highlight the need to consider MNP coexistence in PFAS monitoring and underscore the importance of further studies under environmentally realistic conditions.