Dynamic Monitoring of Temporal Metabolomic Perturbations in Nile Tilapia Induced by PFOA Using Homemade Extraction Electrospray Ionization Mass Spectrometry.

Persistent organic pollutants, represented by perfluorooctanoic acid (PFOA), have traditionally been evaluated for aquatic toxicity through static end point analyses, particularly lacking time-series analyses of dynamic metabolic pathways. This study integrated noninvasive skin mucus sampling with extractive electrospray ionization mass spectrometry (EESI-MS) to, for the first time, longitudinally and continuously track metabolic trajectories in individual Nile tilapia exposed to PFOA (0.2-20 μg/L) over 21 days. Dynamic responses of oxidative stress biomarkers and metabolomic profiles were systematically characterized through integrated analyses. Utilizing the three-dimensional extraction-ionization capability of EESI-MS, the temporal dynamics of 249 differential metabolites were captured, revealing a three-stage progression of toxicity: in the early exposure stage (days 1-3), histidine metabolism was activated to alleviate oxidative stress; in the midstage (days 7-14), glutathione and arachidonic acid metabolism were enhanced, signaling the initiation of antioxidant defense and inflammatory cascades; in the late stage (day 21), tryptophan metabolic disturbances may have triggered neurological dysfunction. The study unveils the progressive toxicity mechanism of PFOA from oxidative damage to neurotoxicity, providing a transformative monitoring paradigm for real-time risk assessment and ecological toxicity classification of per- and polyfluoroalkyl substances (PFASs) in aquatic environments.