Magnetic solid-phase extraction based on tetrabenzyl modified Fe3O4 nanoparticles for the analysis of trace polycyclic aromatic hydrocarbons in environmental water samples

A novel sorbent for magnetic solid-phase extraction, 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane (TBCD) modified magnetic nanoparticles, was synthesized in this work. The four benzyl groups of TBCD provide the Fe3O4-TBCD nanoparticles with strong adsorption capacity for polycyclic aromatic hydrocarbons (PAHs) due to their pi-pi stacking interaction, which increases selectivity of the synthesized material to target analytes. The prepared material was characterized by scanning electron microscopy, X-ray diffraction patterns, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The results indicated that the Fe3O4-TBCD nanoparticles were successfully prepared, and the particles were homogeneous nanospheres with excellent magnetic properties. Based on the optimized extraction conditions, a rapid and effective method was developed for the pre-concentration of PAHs from environmental water samples by combination with high performance liquid chromatography (HPLC). Satisfactory precision and accuracy of the developed method were obtained in a low concentration range of 0.3 ng L-1 to 1.2 x 10(3) ng L-1. This method produced lower limits of detection in the range of 3.0 x 10(-2) ng L-1 to 1.2 ng L-1. The high pre-concentration rate and efficiency of the method ensure its successful application in extraction of trace PAHs from large volumes of environmental water samples. The extraction recoveries in environmental water samples ranged from 81.1% to 115.5% with the relative standard deviations (n = 5) less than 10%.