Lignosulfonate-modified electrode for electrocatalytic reduction of acidic nitrite

Sodium lignosulfonate (LS) undergoes oxidative electropolymerization on a glassy carbon (GC) electrode from sulfuric acid solution to form a chemically modified electrode exhibiting anionic character and redox activity. Cyclic voltammetry reveals the existence of two redox systems at E degrees' values of +0.29 and +0.53 V, respectively. Peak currents are proportional to the scan rate as expected for surface confined systems. The GC I poly-LS electrode shows electrocatalytic activity toward the reduction of acidic nitrite. When operating in a constant potential amperometric mode (at 0.0V, vs. Ag/AgCl), a linear relationship between nitrite concentration and reduction current is observed over the range of 1 to 250 mu M. The detection limit reaches 0.3 mu M (S/N = 3). The electrode may be practically applied for nitrite determination in human saliva.