Fe3O4 Magnetic Nanoparticles as Peroxidase Mimetics Used in Colorimetric Determination of 2,4-Dinitrotoluene

Abstract Fe 3 O 4 magnetic nanoparticles (Fe 3 O 4 MNPs) were prepared by co-precipitation method, which possessed intrinsic peroxidase-like activity. It was found that the as-prepared Fe 3 O 4 MNPs could not only catalyze the oxidation of peroxidase substrate, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate acid) (ABTS) by H 2 O 2 to produce the colored product with maximum absorbance at 417 nm, but also catalyze the oxidation of 2,4-dinitrotoluene (DNT) by H 2 O 2 and thus consume H 2 O 2 in the reaction system. On the basis of the reaction mechanism described above, a novel colorimetric reaction system of Fe 3 O 4 MNPs-ABTS-H 2 O 2 -DNT was established for the determination of trace amount of DNT. Some key influencing factors of the proposed Fe 3 O 4 MNPs-ABTS-H 2 O 2 -DNT system were systematically discussed and optimized. Under the optimal conditions, the absorbance of the system at 417 nm displayed a good linear relationship with DNT concentration in the range from 5.0 × 10 −7 M to 2.0 × 10 −5 M with a detection limit of 1.5 × 10 −7 M ( S/N = 3). These results demonstrated that the constructed colorimetric method was simple, rapid and sensitive enough for the detection of DNT, which would have a great potential in the application of on-line monitoring of DNT in environmental water samples