Magnetic nanoparticles with hydrophobicity and hydrophilicity for solid-phase extraction of polycyclic aromatic hydrocarbons from environmental water samples

Magnetic nanoparticles (MNPs) featured with divinylbenzene (DVB) and sulfonate functionalities (Fe3O4-DVB-SO3−) were prepared via “thiol-ene” click chemistry. The hydrophobic DVB moieties were dedicated for extraction while the hydrophilic sulfonate groups were designed for dispersing the MNPs in aqueous sample solution. Thus, the specially designed material could ensure operational convenience and improve reproducibility during extraction. The application of the material was demonstrated by the extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples followed by gas chromatography-mass spectrometric analysis. The main factors influencing the extraction, including the type of the desorption solvent, the agitation mode, the amount of MNPs, extraction and desorption time and salt addition in sample solution, were investigated in detail. Under the optimized conditions, the proposed method showed satisfactory reproducibility with intra-day and inter-day relative standard deviations less than 16.5% and 21.2%, and low limits of detection of 1.1 pg mL−1, 0.8 pg mL−1, 1.1 pg mL−1, 1.4 pg mL−1, 0.6 pg mL−1, 2.1 pg mL−1 and 0.7 pg mL−1 for naphthalene, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene and pyrene, respectively. The developed method was also successfully used for determination of the PAHs in genuine lake and river environmental water samples by standard addition method. All the studied PAHs were detected in these waters with comparable results by the standard liquid-liquid extraction method. The developed MNPs with dual property of hydrophobicity and hydrophilicity were suitable for the treatment of water samples. The magnetic solid phase extraction based on this material was reliable and convenient. It has great potential in the preconcentration of trace analytes in complex matrix.