Magnetic nanofibrous polyaniline nanocomposite for solid-phase extraction of naproxen from biological samples prior to its spectrofluorimetric determination

Nanofibrous polyaniline-magnetite (PANI/Fe3O4) nanocomposite was in situ prepared through adsorption of magnetite nanoparticles onto PANI nanofibers surface and utilized as an efficient sorbent for magnetic solid-phase extraction of naproxen from water and biological samples, followed a desorption step and spectrofluorimetric determination. Field-emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, thermal gravimetric analysis and X-ray diffraction techniques were employed for characterization of the prepared nanocomposite. The important parameters influencing the extraction efficiency including PANI/Fe3O4 mass ratio, adsorbent dose, extraction time, sample solution pH, ionic strength, type and volume of desorption solvent and the elution time were studied and optimized. The investigated nanocomposite was successfully applied to the extraction of naproxen in spiked tap water, urine and plasma samples, with a relative recovery in the range of 90-98%. The reusability of PANI/Fe3O4 was examined for ten successive cycles, and the results confirm that the efficiency did not change significantly. A linear calibration plot was obtained in the range of 40-1000 ng mL(-1) with a limit of detection about 17 ng mL(-1) under the optimum conditions. The relative standard deviation (RSD) was found to be 2.34% (n = 8, concentration level of 100 ng mL(-1)). The kinetics and thermodynamics of the extraction process were also studied.