ISSN:
1040-0397
Keywords:
Carbon paste electrodes
;
Modified electrodes
;
Synergism
;
Voltammetry
;
Adenine
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A new concept of electrode modification is presented, consisting of chemically assisted electrochemical oxidative pretreatment of the electrode surface. If carbon paste electrodes (CPEs) are polarized at +1.75 V (vs Ag/AgCl) in a dilute alkaline medium (1 × 10-3mol/L) containing 0.1 mol/L NaNO3 for 60s, they exhibit a unique ability to preconcentrate adenine, an important biological substance, that served as a model compound. In this work, a thorough study has been performed to explore the new pretreatment procedure, but also its analytical application for trace adenine determination was optimized. During the pretreatment of a CPE, a specific oxide layer is formed due to a synergistic effect of a combined anodic and chemical oxidation process, in which the presence of sodium nitrate plays a crucial role. In a subsequent step under open-circuit conditions, adenine is oxidized by the oxide layer, and the resulting oxidation product is strongly adsorbed onto the electrode surface. After medium exchange, the adsorbed oxidation product of adenine is reduced at -0.5 V (vs. Ag/AgCl) and the voltammetric current response can be utilized for analytical purposes. Applying 10 min accumulation and square-wave voltammetric operation, the detection limit of 20 μg/L (1.5 × 10-7 mol/L) of adenine in a sample solution was acquired. The voltammetric behavior of adenine at plain and pretreated CPEs is also presented and discussed.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/elan.1140071206
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