Voltammetry at Hexamethyl-P-Terphenyl Poly(Benzimidazolium) (HMT-PMBI)-Coated Glassy Carbon Electrodes: Charge Transport Properties and Detection of Uric and Ascorbic Acid.

Matthew Rees,Paolo Bertoncello,Andrew G Wright,Steven Holdcroft

doi:10.3390/s20020443

Matthew Rees, Paolo Bertoncello + Show 2 more

Open Access

https://doi.org/10.3390/s20020443

Copy DOI

Abstract

We describe the voltammetric behavior of an anion-exchange membrane, hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI). The anion-exchange properties of HMT-PMBI chemically modified electrodes were investigated using K4Fe(CN)6 and K2IrCl6 as redox probes. The permselectivity properties of HMT-PMBI chemically modified electrodes were ascertained using tris(2-2’)bipyridyl-ruthenium(II) chloride Ru(bpy)32+. Cyclic voltammetry and chronoamperometry were utilized to extract parameters such as the concentration of the redox mediators inside the films and the apparent diffusion coefficients. We found the concentration of K4Fe(CN)6 and K2IrCl6 redox species within HMT-PMBI-coated films to be on the order of 0.04–0.1 mol·dm−3, and values of Dapp ca. 10−10–10−9 cm2·s−1. To evaluate the possibility of using such a polymer coating in electroanalysis, HMT-PMBI-modified electrodes were utilized for the voltammetric detection of uric acid in artificial urine, Surine® and ascorbic acid in Vitamin C samples. The results showed that HMT-PMBI-coated electrodes can detect uric acid in Surine® with a limit of detection (LoD) of 7.7 µM, sensitivity of 0.14 µA·µM−1·cm−2, and linear range between 5 μM and 200 μM, whereas for Vitamin C tablets, the LoD is 41.4 µM, the sensitivity is 0.08 µA·µM−1·cm−2, and the linear range is between 25 μM and 450 μM.

Highlights

There is ongoing interest in analytical chemistry in developing sensors with high sensitivity and selectivity to detect analytes of clinical interest at low concentrations while minimizing potential interferences
In proton exchange fuel cells (PEMFCs), the ionomer is made of a polymer having a net negative charge that transports protons from the anode to the cathode, whereas in alkaline fuel cells (AFCs), the ionomer is made of a polymer with a net positive charge that transports hydroxide ions from the cathode to anode
We studied for the first time the charge transport properties of a novel ionene derivative, namely hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI), and evaluated its use as a chemically modified electrode for the detection of uric and ascorbic acid

Summary

Introduction

There is ongoing interest in analytical chemistry in developing sensors with high sensitivity and selectivity to detect analytes of clinical interest at low concentrations while minimizing potential interferences. One of the possibilities to obtain the desired sensitivity and selectivity is the modification of electrode surfaces with suitable molecules, so that they will be able to interact and preferentially preconcentrate the analyte of interest This has led to the development of chemically modified electrodes, whose applications have been widely reported in the literature since the 1980s [2,3,4,5,6]. In proton exchange fuel cells (PEMFCs), the ionomer is made of a polymer having a net negative charge (typically sulfonic or carboxylic) that transports protons from the anode to the cathode, whereas in alkaline fuel cells (AFCs), the ionomer is made of a polymer with a net positive charge (typically ammonium or phosphonium) that transports hydroxide ions from the cathode to anode These ion-exchange properties made ionomers suitable as membranes in water electrolyzers and desalination units [12,13,14]. We deposited a film of HMT-PMBI on glassy carbon electrodes and evaluated the charge transport properties with respect to standard negatively charged redox mediators such as K4 Fe(CN) and K2 IrCl6

Methods

Results

Conclusion