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|Type:||Artigo de periódico|
|Title:||Electrochemical behavior of pyrroloquinoline quinone immobilized on silica gel modified with zirconium oxide|
|Abstract:||Pyrroloquinoline quinone (PQQ) was immobilized on the silica gel surface modified with zirconium oxide, designated as Si:Zr, by the carboxylic groups of the PQQ molecule and the zirconium oxide on the silica surface. The electrochemistry of PQQ immobilized on the Si:Zr matrix, incorporated in a carbon paste electrode, was evaluated using the cyclic voltammetry technique. The Si:Zr:PQQ-modified electrode showed a redox couple at E-m = (E-pa1 + E-pc)/2 = -0.150 V vs SCE at pH 7, close to that observed in aqueous solution, and another oxidation peak, E-pa2 = -0.100 V vs SCE. Studies in different pH solutions in the range of 3-7 showed that the first oxidation peak, E-pa1, is highly dependent on the solution pH shifting from to -0.175 to 0.100 V vs SCE, while E-pa2 remains practically constant at 0.100 V as the pH decreases from 7 to 3. The immobilized PQQ electrode presented the property to electrocatalyze the NADH at 150 mV vs SCE. The effect of addition of Ca2+ ions on the electrode electroactivity for the NADH oxidation was also verified. Different from that observed for the PQQ immobilized on other electrode materials, the Ca2+ ions did not influence the electrocatalytical response; however, the electrode stability was considerably improved in the presence of Ca2+ ions, indicating that the matrix surface has a great influence on the electrochemical behavior of PQQ. (C) 2003 Elsevier Science (USA). All rights reserved.|
carbon paste electrode
|Editor:||Academic Press Inc Elsevier Science|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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