Efficient sorptive extraction of naproxen from biological samples by retrievable polyaniline-magnetite nanocomposite followed by spectrofluorometric determination: Equilibrium, kinetics and thermodynamic study.

Polyaniline-magnetic nanocomposite was prepared[1] and utilized as a sorbent in magnetic solid phase extraction (MSPE) technique for extraction of naproxen with the spectrofluorometric detection system. Field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and X-ray diffraction techniques were employed for characterizing of the prepared polyaniline-magnetic nanocomposite. The extraction efficiency of naproxen by polyaniline-magnetic nanocomposite was investigated in view of equilibrium, kinetics and thermodynamics parameters. The mass ratio of polyaniline (PA) to Fe3O4[2], the amount of adsorbent, contact time, pH value[3] and ionic strength were investigated as the significant influential parameter on extraction efficiency in optimization study. Moreover, type of desorption solvent, volume and the elution time were optimized in the elution step. The high porosity of adsorbent and magnetically retrievable collection[4] provides a convenient approach for the extraction process. Furthermore, the nanocomposite was successfully applied to extraction and determination of naproxen in spiked tap water, urine and plasma sample with a relative recovery percentage in the range of 90-98 %. A linear calibration graph was obtained in the range of 40 to 600 ng•mL-1 with a limit of detection (S/N=3) about 17 ng•mL-1 at the optimum condition. Precision of the method was acceptable with RSD values about 2.34% (n=8) at the concentration level of 1 µg•mL-1.Furthermore, the reusability of PA-Fe3O4 was examined for ten successive cycles and the results confirm that the efficiency did not change significantly. The naproxen adsorption process satisfactorily follows the pseudo second-order kinetic model, which present good agreement between the calculated qe and the experimental ones along with best correlation coefficient values. The thermodynamic parameters were measured and ∆Hº value for naproxen adsorption demonstrates an endothermic process.