Polarographic determination of nitrate and nitrite ions by catalytic wave of vanadium(IV)-cyclohexanediaminetetraacetato complex

Abstract

The polarographic reduction current of 1, 2-cyclohexanediaminetetraacetato-vanadium (IV) complex {V (IV)-CyDTA} in NH4Cl-NH3 buffer solution increased with adding nitrate or nitrite to this solution, that is, a catalytic wave appeared. When the concentration of V(IV)-CyDTA is five times larger than that of nitrate or nitrite ion, the catalytic current is proportional to the concentration of the oxidant. This phenomenon was utilized for the determination of nitrate and nitrite ions. Nitrate or nitrite ion in NH4Cl-NH3 buffer solution was determined at pH 8.6 by this method. Nitrite ion in the mixture of nitrate and nitrite ions could be determined without the influence of nitrate ion by using V(IV)-CyDTA of less than 0.5 mM. However, as the determination of nitrate ion in the mixture was affected by nitrite ion, a calibration curve for nitrate ion in the presence of a known amount of nitrite was obtained by using V(IV)-CyDTA in (110) mM and nitrate ion in the mixture could be determined. This method is useful for the determination of nitrate ion and/or nitrite ion in the mixture of both ions.