Electrocatalytic Reduction of Nitrite Using a Carbon Nanotube Electrode in the Presence of Cupric Ions

A simple, inexpensive method for determining nitrite is presented. With a carbon nanotube modified glass carbon electrode (GC), the overpotential for reduction of nitrite decreased, and direct reduction could be achieved in acid solution. Sensitivity, however, was not very high. When cupric ions were added to the solution, the reduction peak current increased significantly, and in particular the presence of multiple nitrate did not interfere. Experimental conditions were optimized, and preliminary studies were performed on the electrochemical mechanism of nitrite reduction in the presence of cupric ions on the carbon nanotube modified electrode. Under optimized conditions, the peak current of reduction achieved with the differential pulse voltammetric method was proportional to the concentration of nitrite in the ranges of 2.0×10^–6–1.0×thinsp;10^–5molL^–1 and 2.0×10^–5–1.0×10^–3molL^–1. The detection limit reached 5.0×10^–7molL^–1, and most of the inorganic ions did not interfere. The determination of nitrite in samples of rain water and river water was satisfactory.