Fabrication of poly(4-aminobenzoic acid/o-toluidine) modified carbon paste electrode and its electrocatalytic property to the oxidation of nitrite

Resumo

The poly(4-aminobenzoic acid/o-toluidine) (4-AB/OT) modified carbon paste electrode (CPE) was fabricated by consecutive cyclic voltammetry. The poly(4-AB/OT) CPE shows catalytic activity for the oxidation of nitrite in 0.1 M phosphate buffer solution (pH 7). Due to the electrostatic interaction between the negatively-charged nitrite ions and the positively-charged poly(4-AB/OT) film, the operating potential for nitrite oxidation was shifted about 240 mV to negative side, compared to bare CPE. The catalytic peak current was found to be linear with the nitrite concentration in the range of 6–600 μM, with a correlation coefficient of 0.981, using amperometry. The sensitivity and limit of detection for the poly(4-AB/OT) CPE are about 187.4 μA/mM and 3.5 μM, respectively. The possible interferences from several common ions were tested. The developed sensor was also successfully applied to the determination of nitrite concentration in a mineral water sample.