Spectrophotometric determination of trace amounts of nitrite based on the nitrosation reaction with N,N-bis(2-hydroxypropyl)aniline and its application to flow injection analysis

Abstract

The spectrophotometric determination of nitrite using a new colour reagent was examined and was applied to the determination of nitrite by flow injection analysis (FIA). N,N-Bis(2-hydroxypropyl)aniline reacts with nitrite in an acidic medium to form a reddish product (λ_max.= 500 nm), which gradually changes to a yellowish product (λ_max.= 370 nm). The reddish product was used for the spectrophotometric determination of nitrite. The apparent molar absorptivity was about 2 × 10⁴ l mol^–1 cm^–1. In FIA, the calibration graph was linear from 3 to 64 µg l^–1 of nitrite-nitrogen, and the relative standard deviation for nine determinations was 0.7% when using a solution containing 16 µg l^–1 of nitrite-nitrogen. The sampling rate was 50 h^–1.