A novel solid phase extraction method based on the adsorption of cetyltrimethylammonium bromide (CTAB) on the surface of Fe3O4 nanoparticle adsorbent was developed for determination of ibuprofen in environmental samples. The nanoparticles were structurally and optically characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FT-IR). Main parameters affecting the adsorption recovery of the analyte such as Fe3O4 nanoparticles zeta potential, the amount of surfactant, pH value, desorption conditions, extraction and desorption time, sample volume, and ionic strength were evaluated and optimized. Under the optimum conditions, the method was successfully applied to the determination of ibuprofen in Lap and surface water samples with satisfactory recoveries (96-99%). The effect of humic acids contaminants on the extraction efficiency of ibuprofen was also investigated. The linear range of the method was 0.5-500 ng mL(-1) and a high enrichment factor of 99 and low detection limit of 0.07 ng mL(-1) were obtained. (C) 2014 Elsevier Ltd. All rights reserved