SEMI-CONTINUOUS DETERMINATION OF NO2 IN PASSIVE DIFFUSERS BY FLOW INJECTION/UV-VIS SPECTROPHOTOMETRY

Abstract

In this work the development of a semi-automated method by flow injection for spectrophotometric indirect determination of NO2, is described. The gas of environmental importance is captured through passive diffusers built in the laboratory, where it undergoes a reaction with triethanolamine to form nitrite ions in relation 1:1, which are determined after the derivatization with sulfanilamide and N-(1-naphthyl) ethylenediamine. It’s concluded that the proposal method is quick and easy, as well as sensitive and selective to determine the chemical specie of interest. The estimated NO2 concentration in the air of Saltillo in Coahuila was 2.6 ± 0.3 mg m-3, which was above the maximum recommended by NOM-023-SSA1-1993 norm.

Keywords

• NO2
• nitrites
• UV-VIS spectrophotometry
• flow-injection