Electrocatalytic Oxidation and Determination of Insulin at Rhodamine B –Multi-walled Carbon Nanotubes Modified Glassy Carbon Electrode

The modified electrode surface was provided with the electropolymerization of the rhodamine B in the presence of carbon nanotube (CNT). The modified electrode offers dramatic improvements in the stability and sensitivity of voltammetric measurements of insulin compared to the bare and rhodamine B modified glassy carbon electrodes. The enhanced electrocatalytic activity towards insulin is indicated from lowering the potential of the oxidation process (starting around 0.75 vs. Ag/AgCl) and the substantially higher sensitivity over the entire potential range. A linear dynamic range (100–600 nM) was achieved with a detection limit of 5 nM. The accuracy of the modified electrode was indicated by insulin recovery test in the real samples as human plasma and pharmaceutical samples.