Potentiodynamic Electrochemical Impedance Spectroscopy of Polyaniline-Modified Pencil Graphite Electrodes for Selective Detection of Biochemical Trace Elements.

Adel Yavarinasab,Sajjad Janfaza,Mostafa Abedini,Mina Hoorfar,Nishat Tasnim,Hamed Tahmooressi

doi:10.3390/polym14010031

Abstract

In this study, we analyzed the application of potentiodynamic electrochemical impedance spectroscopy (PDEIS) for a selective in situ recognition of biological trace elements, i.e., Cr (III), Cu (II), and Fe (III). The electrochemical sensor was developed using the electropolymerization of aniline (Ani) on the surface of the homemade pencil graphite electrodes (PGE) using cyclic voltammetry (CV). The film was overoxidized to diminish the background current. A wide range of potential (V = −0.2 V to 1.0 V) was investigated to study the impedimetric and capacitive behaviour of the PAni/modified PGE. The impedance behaviors of the films were recorded at optimum potentials through electrochemical impedance spectroscopy (EIS) and scrutinized by means of an appropriate equivalent circuit at different voltages and at their corresponding oxidative potentials. The values of the equivalent circuit were used to identify features (charge transfer-resistant and double layer capacitance) that can selectivity distinguish different trace elements with the concentration of 10 μM. The PDEIS spectra represented the highest electron transfer for Cu (II) and Cr (III) in a broad potential range between +0.1 and +0.4 V while the potential V = +0.2 V showed the lowest charge transfer resistance for Fe (III). The results of this paper showed the capability of PDEIS as a complementary tool for conventional CV and EIS measurement for metallic ion sensing.

Highlights

Published: 22 December 2021The presence of certain metal ions is an unmet need to drive biological processes in the human body: Any imbalances in that regard can cause serious disorders and malfunctions for living tissues
The repulsion between the cationic metal ions and polymer was balanced by the chelating dopant, which generated the escalated background currents due to the polymer redox and charging reactions
Fe (III) revealed the highest charge transfer and double layer capacitance due to its orbital configuration and paramagnetic property, both of which were selected as the feature extraction for further selectivity

Summary

Introduction

The presence of certain metal ions is an unmet need to drive biological processes in the human body: Any imbalances in that regard can cause serious disorders and malfunctions for living tissues. Apart from the metabolic role of heavy metal ions, one other aspect is that they are usually produced by anthropogenic activities and categorized as pollutants in the environment [3]. What makes it worse is the non-biodegradability of metal ions, which makes them accumulate in living organisms and cause harmful disorders [4].

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