Development, validation, comparison, and implementation of a highly efficient and effective method using magnetic solid-phase extraction with hydrophilic-lipophilic-balanced materials for LC-MS/MS analysis of pesticides in seawater.

To achieve multi-pesticides residue analysis in seawater, hydrophilic-lipophilic-balanced magnetic particles were designed and fabricated by swelling polymerization of divinyl benzene (DVB) and N-vinyl pyrrolidone (NVP) on the surface of Fe3O4@SiO2 magnetic particles. The ratio of DVB to NVP was adjusted to achieve a proper balance in hydrophilicity and lipophilicity. The obtained magnetic particles were systematically characterized by TEM, SEM, FT-IR and vibrating sample magnetization. Based on the optimized magnetic nanoparticles, a sensitive magnetic solid-phase extraction method was developed for the simultaneous pre-concentration and determination of 96-pesticide residues from large-volume seawater samples prior to being detected by liquid chromatography-tandem mass spectrometry. Recoveries of pesticides in spiked seawater samples (0.001, 0.01, 0.1, 1.0 μg L-1) ranged from 62% to 112% with RSDs less than 21%. The method limits of detection of 96 pesticides ranged from 0.13 to 0.42 ng L-1, the method limits of quantification of 96 pesticides ranged from 1.0 to 10 ng L-1. The method was successfully applied to pesticide residue analysis in water samples from Jiulong River Estuary of China, demonstrating the prospects of this technique as a potential method for the rapid determination of trace levels of multi-pesticide residues in seawater.