Solid phase extraction of magnetic carbon doped Fe3O4 nanoparticles

• The mechanism that Fe3O4/C nanoparticles extract PAHs and other analysts is studied.
• Adsorption/desorption property of Fe3O4/C is compared with that of activated carbon.
• Fe3O4/C is used as chromatographic stationary phase for its retention elucidation.
• Hydrophobic interaction plays the dominant role in MSPE process of PAHs by Fe3O4/C.
• Hydrogen bonding/dipole–dipole attraction participates in the MSPE of other analytes.

Carbon decorated Fe3O4 nanoparticles (Fe3O4/C) are promising magnetic solid-phase extraction (MSPE) sorbents in environmental and biological analysis. Fe3O4/C based MSPE method shows advantages of easy operation, rapidness, high sensitivity, and environmental friendliness. In this paper, the MSPE mechanism of Fe3O4/C nanoparticles has been comprehensively investigated, for the first time, through the following three efforts: (1) the comparison of extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) between the Fe3O4/C sorbents and activated carbon; (2) the chromatographic retention behaviors of hydrophobic and hydrophilic compounds on Fe3O4/C nanoparticles as stationary phase; (3) related MSPE experiments for several typical compounds such as pyrene, naphthalene, benzene, phenol, resorcinol, anisole and thioanisole. It can be concluded that there are hybrid hydrophobic interaction and hydrogen bonding interaction or dipole–dipole attraction between Fe3O4/C sorbents and analytes. It is the existence of carbon and oxygen-containing functional groups coated on the surface of Fe3O4/C nanoparticles that is responsible for the effective extraction process.