Mostafa Khoramnia - Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran- Department of Bioelectrochemistry, Institute of Biotechnology, Urmia University, Urmia, Iran; Bank Keshavarzi, Iran
Hossein Tajik - Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran-Department of Medicinal and Industrial Plants, Institute of Biotechnology, Urmia University, Urmia, Iran
Reza Emamali Sabzi - Department of Chemistry, Faculty of Science, Urmia University, Urmia, Iran; Department of Bioelectrochemistry,Institute of Biotechnology, Urmia University, Urmia, Iran
Abdollah Salimi - Department of Chemistry, Faculty of Science, University of Kordestan, Sanandaj, Iran

As heavy metal ions severely harm human health, it is important to develop simple, sensitive andaccurate methods for their detection in environment and food. Electrochemical detection and determinationfeatured with short analysis time, low power cost, high sensitivity and easy adaptability for in-situmeasurement is one of the most developed methods.In this work a platinum electrode modified with multi-walled carbon nanotubes, chitosan and thebismuth film was fabricated and used to simultaneously determine cadmium, mercury, lead and zinc.At first, the surface of the platinum electrode was cleaned using sandpaper, alumina, deionizedwater and an ultrasonic device. As the next step, in order to modify of the electrode surface, modifiedMWCNTs and chitosan composite was coated on the clean and dried surface. Then, usingchronoamperometry technique the bismuth was covered on the composite film by E =-0.8 V, t=40 s. Afterthat deoxygenation was applied to the solution using nitrogen gas in order to get the most sharpnessmercury peak, then preconcentration step started using chronoamperometry technique. After rest time atthe end step, andoing stripping voltammetry was applied using differential pulse voltammetry technique.All of the experimental conditions were optimized, the modified electrode was then applied to theanalysis of Cd (II), Hg (II), Pb (II) and Zn (II). The linear range of the electrode was 0.0003303-0.006098μM for Cd (II), 0.000588-0.004839 μM for Hg (II), 0.055-0.23 μM for Pb (II) and 0.005-0.064 μM for Zn(II). The determination of Cd (II), Hg (II), Pb (II) and Zn (II) in the meat of rainbow trout fish wereperformed and gave satisfactory results in accordance with atomic absorption spectroscopy results.This modified electrode can be self-designed and prepared easy with low costs. This novel sensorcan detect and determine 4 toxic metals simultaneously with high accuracy and sensitivity in minimumtime.

Platinum electrode, MWCNTs, chitosan, bismuth film, heavy metals, anoding stripping voltammetry