Abstract

A poly(aniline-co-m-ferrocenylaniline) was successfully synthesized on a glassy carbon electrode (GCE) by electrochemical copolymerization using a scan potential range from −0.3 to +0.9 V (vs. Ag/AgCl) in 0.5 M H2SO4 containing 30% acetonitrile (ACN), 0.1 M aniline (Ani) and 0.005 M m-ferrocenyaniline (m-FcAni). The field emission scanning electron microscope (FESEM) and electrochemical methods were used to characterize the poly(Ani-co-m-FcAni) modified electrode. The poly(Ani-co-m-FcAni)/GCE exhibited excellent electrocatalytic oxidation of ascorbic acid (AA) in citrate buffer solution (CBS, pH 5.0). The anodic peak potential of AA was shifted from +0.55 V at the bare GCE to +0.25 V at the poly(Ani-co-m-FcAni)/GCE with higher current responses than those seen on the bare GCE. The scan number at the 10th cycle was selected as the maximum scan cycle in electrochemical polymerization. The limit of detection (LOD) was estimated to be 2.0 μM based on the signal-to-noise ratio (S/N = 3). The amperometric responses demonstrated an excellent selectivity for AA determination over glucose (Glu) and dopamine (DA).

Highlights

  • L-Ascorbic acid (AA, vitamin C) is the major antioxidant found in many plants

  • In order to optimize the experimental conditions for measurement of ascorbic acid (AA) oxidation at the poly(Ani-co-m-FcAni)/glassy carbon electrode (GCE), the effect of the applied potential and scan cycle used for synthesis of the poly(Ani-co-m-FcAni) was investigated

  • A chemically modified GCE based on poly(Ani-co-m-FcAni) was successfully prepared by electrochemical copolymerization in 0.5 M H2SO4 containing 30% ACN, 0.1 M Ani and 0.005 M m-FcAni

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Summary

Introduction

L-Ascorbic acid (AA, vitamin C) is the major antioxidant found in many plants. As known, AA is an essential nutrient that has been widely used on a large scale as an antioxidant agent in foods, beverages and pharmaceutical applications, due to its participation in several human metabolic reactions [1]. The analytical determination of AA has been reported by many methodologies, such as enzymatic methods [2], iodometric titration using 2,6-dichlorophenol-indophenol as indicator [3], spectroscopy [4], chromatography [5], fluorimetry [6] and electrochemistry [7,8] Due to their quick response, high sensitivity, low detection limit and simple use, electrochemical methods are currently of much interest for AA determination by the electrocatalytic oxidation reaction on conventional electrodes. Applications of modified electrodes in electrocatalysis and sensors have been enriched by the specific properties of conducting polymers These are e.g., polypyrrole, polyaniline and polythiophene. Ferrocene may be toxic and pollute to environment, if used on a large scale in the synthetic process for preparation of modified electrodes It would be useful if the ferrocene could be covalently bonded to the matrix, which is used to modify the conventional electrodes in order to investigate novel properties as mentioned above. To explore its potential applications, the prepared electrode was used as a chemical sensor for the electrocatalytic oxidation of AA

Chemicals and Solutions
Synthesis of m-FcAni
Instruments and Measurement Set Up
Results and Discussion
Electrocatalytic Oxidation of AA
Effect of the Applied Potential and Scan Cycle
Amperometric Measurement
Conclusions
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