Measurement of low concentrations of NO2 gas by differential optical absorption spectroscopy method

The availability of inexpensive light emitting diodes (LEDs) makes them an excellent source of light in active Differential Optical Absorption Spectroscopy (DOAS) to measure and monitor trace toxic gases. In this paper, we report the experimental details and outcomes of a new setup developed to detect low concentrations of toxic NO2 gas based on active DOAS with a white light emitting diode employed as the light source. A detection limit of 0.2 part per million (0.4 mg/m(3)) is achieved per meter of path length with a total collection time of 5 s. The achieved detection limit makes the developed setup suitable for real-time industrial monitoring of NO2 emissions at atmospheric pressure. (C) 2019 Elsevier Ltd. All rights reserved.