In this article, C-18/NH2 mixed group modified Fe3O4/SiO2 magnetic nanoparticles (Fe3O4/SiO2/C-18 + NH2 MNPs) were successfully synthesized and used for the extraction of perfluorinated compounds (PFCs) from large volume of water solution. The Fe3O4/SiO2/C-18 + NH2 MNPs, about 25 nm in diameter, possess high extraction ability to the anionic organic pollutants due to the dual function of hydrophobic octadecyl group and cationic aminopropyl groups at low pH. More than 90% of the targets can be extracted from 500 mL of water solution with 0.1 g of the MNP sorbent at pH 3. Twenty min is sufficient to reach adsorption equilibrium, and the targets can be desorbed from the sorbent readily with 12 mL of alkalized methanol after magnetic separation. Simplified extraction procedure could be achieved because of the superparamagnetism and high saturation magnetization of the sorbent (44 emu g(-1)). Therefore, preconcentration of trace level of PFCs from water solution can be performed by using this Fe3O4/SiO2/C-18 + NH2 MNP sorbent which are stable for multiple reuses. (C) 2011 Elsevier Inc. All rights reserved.