A New Method for Atmospheric Nitrogen Dioxide Measurements Using the Combination of a Stripping Coil and Fluorescence Detection

Abstract

A new stripping coil for the collection of nitrogen dioxide (NO2) has been developed to increase its versatility and efficiency. Nitrogen dioxide measurements based on quantitative collection through a reaction coil into an alkaline solution has been examined. Nitrogen dioxide is collected in a 0.1 N NaOH solution. This collection system has an efficiency of nearly 100%. The absorbed nitrogen dioxide has been measured by fluorescence detection with sub-ppbv detection limits. The excitation wavelength at 360 nm and the produced emission wavelength at 405 nm were suitable for nitrite ion measurements.

Mechanism of the NO2 Conversion to NO2− in an Alkaline Solution

“…(2) was second order for NO2 and OH -and its rate constant was calculated as 130 M -1 s -1 in our previous study. 11 Since Eqs. (1) and (2) Column and detector temperature 40˚C the optimum conditions of the two parameters were arranged to secure the occurrence of Eq.…”

“…3 mm, 19-turn) for gas-liquid reaction and detectors. 11 The gaseous NO2 was fed into the stripping coil and put in contact there with the alkaline solution that was also fed into stripping coil with a peristaltic pump. The gas flow rate and the absorption solution flow rate are 150 cm 3 min -1 and 0.6 cm 3 min -1 , respectively.…”