Standardization of Kinetic Determination of Nitrite Based on Its Catalytic Effect on an Indicator Reaction

Abstract

A catalytic kinetic procedure for nitrite determination based on its catalytic effect on the oxidation of brilliant cresyl blue (BCB) by bromate ion in acidic media is standardized and proposed. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of BCB at its λ_max 595nm. The calibration
graph is linear from 1-80 ng.ml^–1 of nitrite. The detection limit is
5.8 ng.ml^–1 of nitrite. Nitrite in the range of 10–80 ng.mL^–1 has
been determined successfully where recoveries were 97.3 ∼ 103.7%
with the relative standard deviation 0.1 ∼ 0.8%. The effect of many
foreign ions upon determination of 70 ng.mL^–1 of nitrite has been
studied and shown that most common cations and anions do not
interfere in the determination except Fe²⁺ which was masked. The
procedure was successfully applied for the determination of nitrite
in wastewater and seawater with satisfactory results. The typical
feature of this procedure is that the determination could be carried
at normal temperature of 25ºC with analysis time of 4 min.