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Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

journal contribution
posted on 06.12.2017, 00:00 by Sushil Kumar, Victoria Vicente-Beckett
Multi-walled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA) by square-wave voltammetry (SWV). The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified) electrode. The peak current was about 3-fold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd). Peak currents increased with increasing ascorbic acid concentration (dynamic range=0.0047-5.0 mmol/L) and displayed good linearity (R2 = 0.994). The limit of detection was 1.4 mmol/L AA, while the limit of quantitation was 4.7 mmol/L AA. The modified electrode was applied to the determination of ascorbic acid in four brands of commercial orange juice products. The measured content agreed well (96-104%) with the product label claim for all brands tested. Recovery tests on spiked orange juice samples showed good recovery (99-104%). The reliability of the SWV method was validated by conducting parallel experiments using high-performance liquid chromatography (HPLC) with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (p=0.05).

Funding

Category 1 - Australian Competitive Grants (this includes ARC, NHMRC)

History

Volume

3

Start Page

388

End Page

396

Number of Pages

9

eISSN

2190-4286

Location

Frankfurt am Main, Germany

Publisher

Beilstein - Institut

Language

en-aus

Peer Reviewed

Yes

Open Access

Yes

External Author Affiliations

Centre for Plant and Water Science; Institute for Resource Industries and Sustainability (IRIS);

Era Eligible

Yes

Journal

Beilstein journal of nanotechnology.

Exports