A dual electrochemical sensor for nitrite and nitric oxide

Abstract

Nafion/lead-ruthenate pyrochlore chemically modified electrode (NPyCME) showed a remarkable dual sensing activity toward NO₂⁻ oxidation and NO reduction as demonstrated by cyclic voltammetry (CV), ac-impedance spectroscopy and flow injection analysis (FIA). The mechanistic parameters of current function, charge transfer resistance and exchange current for the NPyCME, GCE and Nafion-coated GCE were evaluated and compared. The disproportionation reaction of N^IIIO₂⁻ into N^IVO₃⁻ + N^IIO in acidic solution was used as a model system for testing the dual sensing ability of the NPyCME. The obtained crossover peak response for NO₂⁻ oxidation and NO reduction in pH 1.65 buffer solution gave the direct proof for the applicability of the NPyCME in the dual electrocatalytic action. By flow injection analysis, under optimized conditions, the calibration curve was linear in the range of 100 nM–100 µM and 800 nM–63.3 µM and the detection limit (S/N = 3) was 4.8 nM and 15.6 nM for NO₂⁻ and NO, respectively.