Highly sensitive and selective amperometric determination of nitrite using electropolymerized film of functionalized thiadiazole modified glassy carbon electrode

This paper reports a highly sensitive and selective determination of nitrite at physiological pH using electropolymerized film of 5-amino-1,3,4-thiadiazole-2-thiol(p-ATT) on glassy carbon electrode (GCE) by amperometry. Bare GCE oxidizes nitrite at 0.96 V in the first cycle and in the subsequent cycles the oxidation peak was shifted to 1.03 V with decreased peak current. However, p-ATT modified electrode oxidizes nitrite at 0.84 V with an enhanced peak current and this oxidation peak was very much stable in the subsequent cycles. Using amperometric method, we achieved the lowest detection of 50 nM nitrite for the first time. Further, the amperometric current increases linearly while increasing the nitrite concentration from 5.0 x 10(-8) to 1.6 x 10(-5) M and a detection limit was found to be 340 pM (S/N = 3). The modified electrode was used to determine nitrite in the presence of 1000-fold excess interferents such as Na+, F-, Ca2+, Cl-, Mg2+, SO42-, NH4+, K+, CO32-, NO3-, glucose, urea and oxalate. The practical application of the present method was successfully applied to the determination of nitrite in water samples. (C) 2009 Elsevier B.V. All rights reserved.