Ultrahigh performance liquid chromatographic analysis and magnetic preconcentration of polycyclic aromatic hydrocarbons by Fe₃O₄-doped polymeric nanoparticles

This paper reports the synthesis of hydrophilic-hydrophobic magnetic Fe₃O₄-doped polymeric nanoparticles (MPNP) and its application for preconcentration of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples for ultrahigh performance liquid chromatographic (UHPLC) analysis. The MPNP were prepared from highly charged poly(styrene-divinylbenzene-co-4-vinylbenzenesulfonic acid sodium salt) nanoparticles impregnated with Fe²⁺ via the electrostatic attraction and by microwave heating. The MPNP are relatively uniform in size with an average diameter of 50nm and have a magnetic saturation value of 24.5emu/g. The hydrophilic-hydrophobic MPNP could easily disperse in water. The phenyl moieties of MPNP assist the adsorption of PAHs via both hydrophobic and π-π interactions. The separation of the PAHs-adsorbed MPNP from water could be easily achieved by a permanent magnet and the adsorbed PAHs were back extracted into acetonitrile for UHPLC analysis. The UHPLC separation of PAHs is very quick and could be achieved within 1.6min. Factors affecting the extraction and desorption were investigated in detail. Under the optimum experimental conditions, the recoveries of various PAHs including acenaphthylene, anthracene, fluoranthene, fluorene, phenanthrene, and pyrene in water samples at three different concentrations are 75.7-102.9, 77.8-101.2, 86.3-100.7, 88.5-99.7, 92.0-106.4, and 81.6-98.5%, respectively. The recovery SDs are 0.30-8.20% and the instrumental limits of detection are 10.83-18.53nM. The proposed technique combining hydrophobic extraction and magnetic separation coupled with UHPLC could provide a fast, convenient and sensitive method for the determination of PAHs in water samples.