All magnetic extractions were performed at neutral pH with a fixed pollutant-SPIONs ratio (7 mL à 1 µM of PCB, i.e., 7 nmol were treated with 5.0 ± 0.1 mg of SPIONs). This ratio was deliberately chosen to enable quantitative comparison between the systems. Such low concentrations require robust analytical quantification. Based on recommendations by the United States Environmental Protection Agency on quantification of PCBs, this was achieved by washing the adsorbent systems after magnetic water cleaning with hexane to resolubilize all non-covalently collected pollutants followed by analysis via GC-MS. To each sample an internal standard (decachloro-1,1'-biphenyl, PCB 209) at a fixed concentration was added.