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Cetyltrimethylammonium Bromide-Coated Fe3O4 Magnetic Nanoparticles for Analysis of 15 Trace Polycyclic Aromatic Hydrocarbons in Aquatic Environments by Ultraperformance, Liquid Chromatography With Fluorescence Detection

Wang, Hao, Zhao, Xiaoli, Meng, Wei, Wang, Peifang, Wu, Fengchang, Tang, Zhi, Han, Xuejiao, Giesy, John P.
Analytical chemistry 2015 v.87 no.15 pp. 7667-7675
adsorption, adverse effects, aquatic environment, calcium, cetyltrimethylammonium bromide, cost effectiveness, dissolved organic matter, fluorescence, hardness, hydrophobicity, liquid chromatography, liquid-liquid extraction, magnesium, magnetite, nanoparticles, polycyclic aromatic hydrocarbons, rain, river water, solid phase extraction, surface water, tap water, wastewater
Accurate determination of polycyclic aromatic hydrocarbons (PAHs) in surface waters is necessary for protection of the environment from adverse effects that can occur at concentrations which require preconcentration to be detected. In this study, an effective solid phase extraction (SPE) method based on cetyltrimethylammonium bromide (CTAB)-coated Fe₃O₄ magnetic nanoparticles (MNPs) was developed for extraction of trace quantities of PAHs from natural waters. An enrichment factor of 800 was achieved within 5 min by use of 100 mg of Fe₃O₄ MNPs and 50 mg of CTAB. Compared with conventional liquid–liquid extraction (LLE), C18 SPE cartridge and some newly developed methods, the SPE to determine bioaccessible fraction was more convenient, efficient, time-saving, and cost-effective. To evaluate the performance of this novel sorbent, five natural samples including rainwater, river waters, wastewater, and tap water spiked with 15 PAHs were analyzed by use of ultraperformance, liquid chromatography (UPLC) with fluorescence detection (FLD). Limits of determination (LOD) of PAHs (log Kₒw ≥ 4.46) ranged from 0.4 to 10.3 ng/L, with mean recoveries of 87.95 ± 16.16, 85.92 ± 10.19, 82.89 ± 5.25, 78.90 ± 9.90, and 59.23 ± 3.10% for rainwater, upstream and downstream river water, wastewater, and tap water, respectively. However, the effect of dissolved organic matter (DOM) on recovery of PAHs varied among matrixes. Because of electrostatic adsorption and hydrophobicity, DOM promoted adsorption of Fe₃O₄ MNPs to PAHs from samples of water from the field. This result was different than the effect of DOM under laboratory conditions. Because of competitive adsorption with the site of action on the surface of Fe₃O₄ MNPs for CTAB, recoveries of PAHs were inversely proportional to concentrations of Ca²⁺ and Mg²⁺. This novel sorbent based on nanomaterials was effective at removing PAHs at environmentally relevant concentrations from waters containing relevant concentrations of both naturally occurring organic matter and hardness metals.