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Portugaliae Electrochimica Acta
Print version ISSN 0872-1904
Port. Electrochim. Acta vol.22 no.2 Coimbra 2004
Electrocatalysis and Determination of Ascorbic Acid Through Graphite Paste Electrode Modified With Iron Nitroprusside
Devaney R. do Carmo, Ricardo M. da Silva, Nelson R. Stradiotto*
Instituto de Química, Universidade Estadual Paulista (UNESP) CEP 14800-900 Araraquara, SP Brasil.
Received 25 October 2002; accepted in revised form 9 January 2004
Abstract
Iron nitroprusside, Fe(II)NP was incorporated into a carbon paste electrode and the electrochemical studies were performed by cyclic voltammetry. The cyclic voltammogram of the modified electrode, Fe(II)NP showed two redox couples ( E½ox)1 = 0.24 and (E½ox)2 = 0.85 V vs. SCE attributed to Fe(II)/Fe(III) and Fe(II)(CN)5NO / Fe(III)(CN)5NO, respectively. The redox couple at (E½ox)1 = 0.24 V presents an electrocatalytic response for ascorbic acid. The modified paste electrode exhibits a decrease of 180 mV in the ascorbic acid oxidation. The modified graphite paste electrode gives a linear range from 1.0 × 10-3 to 2.6 × 10-2 mol L-1 of ascorbic acid with a detection limit of 1.4 × 10-3 (±1.2%) mol L-1 (n =3). The electrocatalytic oxidation of ascorbic acid compounds by the mediator has been used for the determination of ascorbic acid in a commercially pharmaceutical available product .
Keywords: iron nitroprusside, modified electrode, electrocatalysis, ascorbic acid oxidation.
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*Corresponding author. E-mail address: nrstradi@iq.unesp.br