SELECTIVE ELECTROCATALYTIC METHOD FOR THE DETERMINATION OF NITRITE

The reduction of Mo(VI) at -0.48 V vs. SCE in a pH 2.1 solution of 0.1 mM Na2MoO4, 0.1 M KCI results In a deposit on mercury and graphite electrodes which selectively catalyzes nitrite reduction. With linear potential scan voltammetry, a peak is developed at -0.88 V in direct proportion to nitrite concentration over the range 0.01-1 mM. Nitrate does not interfere until it reaches about a 100-fold excess at which point it causes an increase in the analytical current. Neither chloride nor sulfate interfere. Dissolved oxygen causes a correctable increase in the base-line current. The eiectroactlve species was shown to be HNO2- Under the recommended conditions, chemical decomposition was Insignificant for at least 30 min, but sparging the pH 2.1 solution with N2 to remove dissolved oxygen must not exceed 10 min to prevent significant volatility loss. © 1979, American Chemical Society. All rights reserved.