Nitrite Electrochemical Sensor Based on Prussian Blue /Single-Walled Carbon Nanotubes Modified Pyrolytic Graphite Electrode

Nitrite, NO2- (in neutral), and NO (in acidic media) were used as analytical probe to investigate the electrocatalytic properties of Prussian blue nanoparticles (PB) modified edge plane pyrolytic graphite (EPPG) electrode. Results indicate that single-walled carbon nanotubes-Prussian blue hybrid (SWCNT-PB) modified electrode demonstrated greater sensitivity and catalysis towards nitrite compared to PB or a SWCNT modified electrode. The current response of the electrode was reduced in the presence of cetyltrimethylammoniumbromide (CTAB) which was used as a stabilising agent. Electrocatalytic oxidation of nitrite occurred through a simple adsorption controlled electrode reaction. The adsorption equilibrium constant β and the standard free energy change ΔG0 due to adsorption were 4.35 x 103 M-1s-1 (-20.76 kJmol-1) and 15.0 x 104 M-1s-1 (-29.53 kJmol-1) for nitrite and nitric oxide respectively. Despite the adsorption, the EPPGE-SWCNT-PB electrode showed good stability of greater than 80% in the analytes. The electrode's limit of detection and catalytic rate constant were 6.26 µM (4.37 x 106 cm3 mol-1 s-1) and 4.9 µM (6.35 x 105 cm3mol-1s-1) for nitrite and nitric oxide respectively. The fabricated electrode is not difficult to prepare and could serve as a potential sensor for nitrite determination in food and environmental samples.