Polyaniline-functionalized magnetic graphene oxide for dispersive solid-phase extraction of Cr(VI) from environmental waters followed by graphite furnace atomic absorption spectrometry

The present work describes synthesis of polyaniline-coated magnetic graphene oxide (MGO@PANI) as an efficient anion-exchange sorbent for dispersive magnetic solid-phase extraction of Cr(IV) from environmental samples. Graphite furnace atomic absorption spectrometry was used for analysis of the extracts. Synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray analyzer. The important variables on the performance of the method such as pH of sample solution, sorbent amount, extraction and desorption time and type, concentration and volume of desorption elution were thoroughly optimized by means of experimental design and response surface methodology. Under the optimized condition, an aliquot of 50 mL of sample (pH 5.6) was extracted using 40 mg of MGO@PANI nanoparticles during 20 min. Then, the sorbent was desorbed using 850 A mu L of 2.75 mol L-1 H2SO4 under fierce vortex for 4.0 min. A preconcentration factor of 40 and an extraction recovery of 68% were provided by the proposed method. The limit of detection (3S/N) and quantification were obtained as 5.0 and 15 ng L-1, respectively. The method showed a good linearity in the range of 15-300 ng L-1 with determination coefficient of 0.9987. The intra-day precision and inter-day precision (RSD%) were 5.3 and 8.2%, respectively. Finally, different water samples were examined by the proposed method to indicate its real applicability and the results showed good relative recoveries in the range of 100-110%.