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A Simple Colorimetric Detection of Malathion Using Peroxidase Like Activity of Fe3O4 Magnetic Nanoparticles

This study reports synthesis of Fe3O4 magnetic nanoparticles (MNPs) using sodium borohydride (NaBH4). The leach liquor used for the synthesis of MNPs was obtained by citric acid mediated leaching of scrap iron. X-ray diffraction (XRD) analysis showed the presence of magnetite. The MNPs showed super paramagnetic properties with a saturation magnetization (Ms) of 24.628 emu/g. The transmission electron microscopy (TEM) showed spherical shaped MNPs. These Fe3O4 MNPs exhibited intrinsic peroxidase like activity. The optimum concentrations of 3,3′,5,5′-tetramethyl benzidine (TMB), H2O2 and Fe3O4 MNPs for peroxidase like activity were 3 mM, 10 mM and 0.05 mg/ml, respectively. This peroxidase like activity was further used for developing a colorimetric malathion detection method. The increasing concentration of malathion decreased the peroxidase like activity of Fe3O4 MNPs. The peroxidase like activity of Fe3O4 MNPs was completely inhibited at 3000 ppm malathion concentration.