Electrocatalysis and Determination of Ascorbic Acid Through Graphite Paste Electrode Modified With Iron Nitroprusside

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 (E½ ox )1 = 0.24 and (E½ 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 (E½ 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.