Solid-phase extraction and amperometric determination of nitrite with polypyrrole nanowire modified electrodes

In this paper, the electrochemical solid-phase extraction (EC-SPE) and amperometric determination of nitrite with polypyrrole (PPy) nanowire modified electrode was reported. The PPy nanowire modified electrode was prepared by template-free method in a mixture of sodium carbonate and sodium bicarbonate aqueous solution and then conditioned in 0.10 M perchlorate acid for 24 h. EC-SPE (preconcentration) of nitrite ions was conducted under the condition of applied potential 0.800 V for 300 s. The electroreduction of nitrite was conducted under the condition of −0.200 V for 100 s in the solution of 0.50 M H2SO4. The length of nanowires, the temperature and the pH of the test solution, the EC-SPE potential and time have significant effects on the corresponding current. Under a certain condition, the relationship between nitrite concentration and corresponding current density is in good linearity. The determination sensitivity may be varied according to the modification parameters. Under the experimental condition, the highest corresponding sensitivity is 55.84 mA/M cm2, and may be further improved by modification the electrode with longer polypyrrole nanowires.