Synthesis and characterization of Co-Zeolite nanocomposite: electrocatalytic oxidation of methionine

A cobalt-zeolite (CoY) nanocomposite was prepared and used as a modifier for construction of a carbon paste electrode (CoY/CPE) and it was applied for the determination of Methionine (Met). The surface morphology of the nanocomposite was characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), Energy dispersive X-ray analysis(EDX). Particle size of the prepared CoY was in the range between 31 nm and 64 nm. Electrochemical response characteristics of the modified electrode toward Met. were investigated by Cyclic Voltammetry(CV) and Differential Pulse Voltammetry(DP) in a 0.1 M phosphate buffer pH 6.2. A possible mechanism was proposed for the electrochemical response of the electrode toward Met. The electrode showed a suitable linear calibration curve in the concentration range of 3.5×10-7 – 5.5×10-6 mol L-1. The detection limit of the electrode(LOD) and quantification (LOQ) were calculated 9.1×10-8 mol L-1 and 1.3×10-7 mol L-1. Effect of different factors on the response of the electrode such as pH, modifier, electrolyte and scan rate was also studied. It was successfully applied for the determination of Met in serum samples. also the amount of %RSD for evaluation of repeatability and reproducibility of the proposed sensor was obtained 0.13%.