A new chemically modified carbon paste electrode (CPE) was constructed and used for rapid, simple, accurate, highly sensitive, and selective determination of Mo (VI) using differential pulse voltammetry. Molybdenum is an essential trace element for both animals and plants. It has an important role in enzymatic redox reactions. . Because of the low concentration of these metals in food and biological samples, the development of new methods for quantifying trace metals is required and challenged. In some common procedures for the determination of low concentrations of heavy metals a pre-concentration step is needed before performing determination. nanoparticles due to high surface to valume ratio have many sites that used for preconcentration of analytes. In this study nanoparticle of Ni 0.5 Zn 0.5 Fe 2 O 4 for The modified electrode was used. nanoparticle of Ni 0.5 Zn 0.5 Fe 2 O 4 prepared according to the chemical co- precipitation route. The SEM image, XRD pattern and EDS spectrum showed that the Ni 0.5 Zn 0.5 Fe 2 O 4 nanocomposites, synthesized. The synthesized nanocomposite contain Fe, Ni, Zn and O elements and The crystallite size was obtained around 3.5 nm .The electrode was prepared using magnetic nickel zinc ferrite nanocomposite (Ni 0.5 Zn 0.5 Fe 2 O 4 ), as the modifier, in CPE. The cation Mo (VI) was determined after preconcentration at the surface of the modified electrode at -0.7 V vs. Ag/AgCl. Under the optimal conditions, the linear dynamic range and limit of detection was 0.005-1.00 and 0.003 µg/mL, respectively. The effects of different cations and anions on the determination of Mo (VI) was investigated. The results indicated that the electrode is highly selective. Furthermore, the present method was applied to the determination of Mo (VI) in several plant foodstuff samples with satisfactory results.
