Electrochemical Detection Of Heavy Metals In Raw Materials Using a Glassy Carbon Electrode Modified With 4-Aminothiophenol

Abstract

Sensitive and stable electrodes modified with 4-aminothiophenol were developed for heavy metal detection based on coordination bonds between thiol moieties and analyte. The electrodes were modified using diazonium chemistry in a one step modification protocol. The presence of 1,1-diphenyl-2-picrylhydrazyl radical in the electrodeposition media avoids the formation of multilayers and improves the performances due to low surface passivation and good electrochemical transfer at the interface with the solution. Electrodeposition of the organic layer on the electrode surface by chronopotentiometry allowed a good control of the electrode modification process, avoids passivation, and leads to reproducible layers with improved characteristics in comparison with modifications carried out by cyclic voltammetry or chronoamperometry. The electrode was able to detect Pb(II) by differential pulse voltammetry with a linear range of 2.5 - 400 μg L-1 and the detection limit of 1.2 μg L-1 and Cd(II) with the calibration line in the range of 2.5 - 400 μg L-1 and a detection limit of 1.5 μg L-1. Low interferences were observed and the electrodes were applied for analysis of real samples: fruits pomace and waters.