Determination of Ochratoxin at Nanocomposite Modified Glassy Carbon Electrode Combine with FFT Coulometric Admittance Voltammetry and Flow Injection Analysis

In this work, a new electrochemical techniguetechnique based on combination of FFT Coulometric Admittance Voltammetry (FFTCAV) technique and a nanocomposite electrode was developed for the determination of Ochratoxin A in a flow-injection system. The sensor was designed by deposition of gold nanoparticles on reduced graphene nanosheets mixed with carbon multiwall nanotube and ionic liquid (1-ethyl-3-methyl-imidazolium ethylsulphateas) casted on a glassy carbon electrode. Also, in this technique the sensor response calculated in form of charge changes under the peak by integrating admittance in selected potential range, after subtracting the background admittance. As results, application of the nanocomposite as a modifier can catalyze electron transfer, which causes amplifying the response. Besides, iIt was found the electrode response was proportional to concentrations of Ochratoxin A in range from 0.1 to 200 nM, with a detection limit of 3.7x10(-12) M. The nanocomposite electrode showed good reproducibility, a long-term of usage stability for 90 days. The characterization of the sensor surface was studied by scanning electron microscopy and electrochemical impedance spectroscopy methods.