Electrochemical consequtive detection of NO2– and NO3–

Abstract

Since NO2− often coexists with NO3− in environment and waste fluids, it is important to evaluate precisely the concentrations of NO2− and NO3− simultaneously. A new electrochemical consequtive detection system of NO2− and NO3− was constructed. After the concentration of NO3− in the sample solution was detected using an ion selective electrode (NO3−-ISE), persisting NO2− in the sample solution was oxidized to NO3− using carbon felt as a working electrode. Then, the concentration of NO3− in the sample solution was measured using the NO3−-ISE again, whereas the concentration of NO2− was determined by comparing the results before and after electrolytic oxidation. On the basis of the Coulomb number and via electrolysis, our investigations detected the sample solution’s concentrations of NO2− and NO3− successively, thereby easing the evaluation of the concentration of NO2− for cases above 10−5 mol dm−3.