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|Type:||Artigo de periódico|
|Title:||Electrochemical Investigations Of The Reaction Mechanism And Kinetics Between Nadh And Redox-active (nc)2c6h3-nhoh/(nc)2c6h3-no From 4-nitrophthalonitrile-(nc)2c6h3-no2-modified Electrode|
de Oliveira A.B.
|Abstract:||A simple and sensitive method for the electrocatalytic detection of NADH on a carbon paste electrode modified with a redox-active (NC)2C6H3-NO/(NC)2C6H3-NHOH (NOPH/NHOHPH) electrogenerated in situ from 4-nitrophthalonitrile (4-NPHN) is presented. The electrode modified with 4-NPHN showed an efficient electrocatalytic activity towards the oxidation of NADH with activation overpotential of 0.12 V vs. Ag/AgCl. The formation of an intermediate charge transfer complex is proposed for the charge transfer reaction between NADH and the 4-NPHN-resulting system. The second-order rate constant for electrocatalytic oxidation of NADH, κobs, and the apparent Michaelis-Menten constant KM, at pH 7.0 were evaluated with rotating disk electrode (RDE) experiments, giving 1.0 × 104 mol-1 L s-1 and 2.7 × 10-5 mol L-1, respectively. Employing the Koutecky-Levich approach indicated that the NADH oxidation reaction involves two electrons. The sensor provided a linear response range for NADH from 0.8 up to 8.5 μmol L-1 with sensitivity, detection, quantification limits and time response of 0.50 μA L μmol-1, 0.25 μmol L-1, 0.82 μmol L-1 and 0.1 s, respectively. The repeatability of the measurements with the same sensor and different sensors, evaluated in terms of relative standard deviation, were 4.1 and 5.0%, respectively, for n = 10. © 2008 Elsevier B.V. All rights reserved.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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