Abstract

CARMO, Devaney R. do; SILVA, Ricardo M. da  and  STRADIOTTO, Nelson R.. Electrocatalysis and Determination of Ascorbic Acid Through Graphite Paste Electrode Modified With Iron Nitroprusside. Port. Electrochim. Acta [online]. 2004, vol.22, n.2, pp.71-79. ISSN 0872-1904.

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 ( E_½^ox)₁ = 0.24 and (E_½^ox)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 (E_½^ox)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; oxid ation.

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