Voltammetric Behavior of a Modified Electrode With Azide Copper Octa(3-Aminopropyl)Octasilsesquioxane Composite in the Oxidation of Ascorbic Acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Processo FAPESP: 03/12882-6

A novel nanostructured composite, azide copper octa (3-aminopropyl) octasilsesquioxane (ASCA) was incorporated into a graphite paste electrode and the electrochemical studies were conducted with cyclic voltammetry. The cyclic voltammogram of the modified graphite paste electrode with ASCA (GPE-ASCA), showed one redox couple with formal potential (E(theta)) = 0.30 V and an irreversible process at 1.1 V (vs Ag/AgCl; NaCl 1.0 mol L(-1); v = 20 mV s(-1)). The redox couple with (E(theta)) = 0.30V presents an electrocatalytic response for determination of ascorbic acid. The modified electrode gives a linear range from 1.0x10(-4) - 1.0x10(-3) mol L(-1) (r = 0.998) for the determination of ascorbic acid with detection limit of 6.9x10(-5) mol L(-1) and standard deviation of 2.3% for n = 3. The amperometric sensitivity was 122.1 mA/mol L(-1) for ascorbic acid. The application this electrode was tested and ascorbic acid in three commercial pharmaceutical product (Cebion, Cewin and Redoxon) have been determined.