Submicromolar determination of NADH by means of graphite and glassy carbon electrochemical transducers

Abstract

Reduced nicotinamide adenine dinucleotide (NADH) has been determined at submicromolar levels (the detection limit was 0.05 pmol/L) by using graphitized and glassy carbon electrodes obtained from different sources. Preliminary studies compared the sensitivity, stability, and reproducibility of such sensors during NADH measurements in linear-sweep voltammetry as well as at constant applied potential. High purity graphite carbon from Ringsdorff has been found to be the most suitable for NADH oxidation. To regenerate the electrodes after each voltammetric scan, washing with a large volume of distilled water under stirring conditions is required. When the sensitivity of the electrode decreases drastically, the sensor surface must be ground and polished with alumina. The nature of the carbon surface has a pronounced effect on the NADH response.

Chemical Reversibility and Stable Low-Potential NADH Detection with Nonconventional Conducting Polymer Nanotubule Modified Glassy Carbon Electrodes

“…The ubiquitous use by living cells of β-nicotinamide adenine dinucleotide (NADH) and its oxidized form (NAD + ) as coenzymes for a large number of dehydrogenases has generated numerous studies directed at understanding the parameters that may control the redox activity of these biological cofactors. Although the reversible potential for NADH oxidation is estimated to be −0.32 V vs NHE, the direct oxidation of NADH at bare electrodes in general requires high overpotentials that can be as large as 1.0 V. , With carbon electrodes, , this high overpotential can be decreased by pretreatment, although these surface-modified electrodes are still rapidly deactivated. , Also the fouling of the electrode surface associated with the accumulation of reaction products represents a problem inherent to such anodic detection. Considerable efforts have been devoted to identifying new electrode materials that will reduce the overpotential for NADH oxidation and minimize surface passivation effects.…”

NADH electrochemical sensor for the enzymatic determination of L‐ and D‐lactate and 3‐hydroxybutyrate using a flow injection analysis

“…The use of a mediator to lower the oxidation potential of IVADH could eliminate some electrochemical interferences occurring at high potential values, provided that the interference could not be electrochemically oxidized through the mediator itself at a lower potential. An amperometric sensor based on a spectroscopic graphite rod without any mediator added has been described recently [ 5,6]. In this article, we report several improvements of such a technique, especially in the direction of lowering the detection limit (lactate is determinated in this work at the level of 1 X M with respect to a limit of 5 x 1 0 -~ M previously described [ 5]), enhancing the reproducibility (an RSD of less than 2% was obtained) through the use of a reliable wall-jet amperometric cell and a flow injection procedure, and extending the principle to obtain a 3-hydroxy butyrate sensor suitable for chemicals studies.…”