Preparation of Magnetic Graphene Nanocomposites for Fast Detection of Nitrobenzene in Environmental Water Samples by GC-MS

In this work, magnetic graphene nanocomposites were synthesized via hydrothermal reaction and used as an effective adsorbent to extract and concentrate nitrobenzene in water samples, followed by analysis using gas chromatography-mass spectrometry. The properties of the magnetic nanocomposites were characterized by Fourier transform infrared analysis, transmission electron microscopy, and scanning electron microscopy. The nanocomposites have a distinct structure with the magnetite particles scattered over the surface of the graphene. Due to the unique structure, they not only adsorb the target compound strongly, but also have excellent magnetic response that allows fast separation from water. All the experimental parameters affecting the extraction efficiency, including the amounts of sorbents, eluting solvents and volume, adsorption and desorption time were investigated and optimized. Under the optimum conditions, validation experiments showed a good linearity (r(2) = 0.9999) at the range of 5-1,000 mu g/L, satisfactory precision (RSD of intra-day = 3.3 % and RSD of inter-day = 3.9 %), high recovery of 77.3 % for 500 mu g/L and 82.5 % for 100 mu g/L and 84.7 % for 50 mu g/L, respectively, and low detection limit of 0.01 mu g/L for nitrobenzene in aqueous solutions. Finally, the magnetic graphene nanocomposites were successfully applied to detect nitrobenzene in real-world water samples and showed promising results.