A Rapid and Sensitive Colorimetric Reagent for Nitrogen Dioxide in Air

The oxides of nitrogen and their detection in automotive exhaust

“…There are a number of modifications on the Saltzman method. One reported by Lyshkow (16) improves the rate of color development, sensitivity and longer shelf-life of the reagent by adding a promoter (11-salt), and optimizing the concentrations of diazotizing and coupling reagents. The R-salfc used was 2napthol-3,6-disulfonate.…”

NO2 Measurements with RGB Sensors for Easy In-Field Test

“…Figure 1a shows the UV-vis reflectance spectra of the GS-soaked pads exposed to different concentrations of NO2 for 5 min. The spectra are dominated by an asymmetric absorption band centered around 540 nm [3], which is the responsible of the characteristic deep-purple coloration developed by the GS reagent in presence of NO2. It was determined that the reflectance at 540 nm presented, approximately, an exponential dependence on the NO2 concentration.…”

Highly Specific and Wide Range NO2 Sensor with Color Readout

“…(5) This is a non-reversible process that consumes the available indicator molecules in the white state. Considering a 1 st order reaction in [INDW] and an n-th order reaction in [NO2 air] (NO2 involves a multi-step reaction such as hydrolyzation 14 and diazotization 15 ) the process can be modeled by the following set of equations:…”