Covalent organic frameworks-derived magnetic solid phase extraction approach for enrichment and trace detection of...

N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), a widely used rubber antioxidant, and its ozonolysis derivative, 6PPD-quinone (6PPD-Q), have recently attracted significant attention due to their toxic effect in urban runoff mortality syndrome and widespread occurrence in aquatic environments. In this study, a magnetic covalent organic framework (Fe₃O₄@TpPa-NO₂) was synthesized and applied as a magnetic solid-phase extraction (MSPE) adsorbent for the selective extraction of environmentally relevant levels of 6PPD and 6PPD-Q from road runoff, Pearl River water, tap water and human urine samples. The nanocomposite exhibited a uniform spherical morphology, high surface area, well-defined mesoporous structure and strong magnetic responsiveness, enabling rapid efficient analyte capture via synergistic hydrogen bonding and π-π stacking interactions. Critical adsorption parameters were systematically optimized to enhance the overall performance. Combined with ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), the developed method demonstrated good sensitivity (limit of detection: 0.004-0.005 μg L^-1), high linearity (R² ≥ 0.9942) and qualified recoveries (70.2-112.0 %) in real samples. The concentrations of 6PPD and 6PPD-Q ranged from 0.013 to 0.15 μg L^-1, further highlighting the widespread occurrence in aquatic environments. Compared to traditional pretreatment methods, the Fe₃O₄@TpPa-NO₂-based MSPE method offers a sensitive and reliable approach for monitoring rubber-derived pollutants in environmental and biological samples.