Electrochemical determination of ascorbic acid at p-phenylenediamine film-holes modified glassy carbon electrode

Abstract

In this work the determination of ascorbic acid (AA) at glassy carbon electrode (GCE) modified with a perforated film produced by reduction of diazonium generated in situ from p-phenylenediamine (PD) is reported. Holes were intentionally created in the modifier film by stripping a pre-deposited gold nanoparticles. The modified electrodes were electrochemically characterized by common redox probes: hydroquinone, ferrocyanide and hexamineruthenium(III). The cyclic voltammetric and amperometric response of AA using the modified electrodes was compared with that of bare GCE. The bare GCE showed a linear response to AA in the concentration range of 5 mM to 45 mM with detection limit of 1.656 mM and the modified GCE showed a linear response to AA in the concentration range of 5 ?M to 45 ?M with detection limit of 0.123 ?M. The effect of potential intereferents on amperometric signal of AA at the modified GCE was examined and found to be minimal. The inter-electrode reproducibility, stability, and accuracy were determined. The modified electrode showed excellent inter-electrode reproducibility, accuracy and stability. The modified electrode reported is a promising candidate for use in electroanalysis of AA.

Selective electrochemical determination of dopamine at p-nitroaniline film-hole modified glassy carbon electrodes

“…This procedure is similar to what we have reported before [35] on p-phenyldiamine film. First, AuNPs were pre-electronuclated in three rounds as described in before.…”

“…As shown in Figure 1B, the magnitude of the oxidation peak current (for gold stripping) decreases in subsequent cycles indicating removal of the deposited AuNPs. Due to the presence of excess chloride in the solution, the stripping of electronucleated gold by electro-oxidation is encouraged as the stripped gold forms its water-soluble chlorocomplex [35]. 6 …”

“…The fabrication procedure is almost the same to that of the report by Olana et al [35] except the pphenyldiamine film was replaced by the PNA film. Briefly, the major steps were sequential electronucleation of gold nano particles (AuNPs) on GCE (three rounds), grafting of diazonium film from PNA on GCE modified with AuNPs and stripping of the nucleated AuNPs (Scheme 1).…”

“…Then, it was further polished to a mirror finishing with alumina slurries (0.3 µm, BASi) and rinsed carefully with distilled water. The procedure reported by Soreta et al [34,35] was used for electrochemical conditioning of the electrodes used.…”

“…The presence of holes on the PNA film hole modified GCE have further enhanced the Ru(NH 3 ) 6 3+ signal due to change in diffusion mode of the cationic redox probes towards nanoelectrodes. The change in the mode of transport of ions at the hole modified film electrode could be from planar to three dimensional diffusion [35].…”