A micro-impinger sampling device for determination of atmospheric nitrogen dioxide

Abstract

There is an increasing demand for the determination of gaseous pollutants present in both outdoor and indoor environments. It is the result of a growing awareness that good air quality is fundamental to the health of the population. Gas monitors capable of reliable measurements are a global necessity. In this work, we developed a low cost and portable microsampler for gaseous pollutants, using a µ-impinger bubbler containing 500 µL of absorbing reagent. The microsampler was evaluated in the detection of NO2 using the Griess-Saltzman reagent (GS). The µ-impinger enabled the determination of NO2 concentrations lower than 15 µg m–3 (~8 ppb) using a 50 mL min–1 sample flow rate during 30 min. This NO2 concentration is 10 times lower than the EPA air quality standard. In the calibration procedure, standard atmospheres with NO2 concentrations from 15 to 165 µg m–3 were used. The limit of detection was 14 µg m–3 considering 3.3 times the standard deviation of the blank signal. The relative error was 12.0%, and the coefficient of variation was 6.9%. The portable sampling procedure can be used in remote areas where there is no public electricity supply. The detection limit could be improved further by using longer sampling times and/or higher sampling flow rates. The method is selective and highly sensitive.