A new droplet method has been developed for the determination of nitrogen dioxide in air. The method based on the reaction of nitrite with sulfathiazole in acidic medium and then coupled with NEDA (N naphthylethylenediamine dihydrochloride). The reaction product (azo dye) has an absorption maximum at 546 nm . The developed system describe the coupling of the sampling device behavior of the liquid droplet using a wind tunnel method. Nitrogen dioxide was used as a test gas. The feature of the droplet such as droplet flow rate, effect of time on the droplet size and the effect of droplet size has been studied. A linear calibration curve at different relative humidity (%) was obtained between: the concentration of NO2 obtained by the droplet method and NO2 in the wind tunnel. The proposed method is sensitive to measure NO2 in air at μg L-1 . Nitrogen dioxide is fixed as nitrite using 3% triethanolamine (TEA) trapping solution. The effect of outer diameter valve on droplet as well as the wind velocity is well addressed in this paper. The main advantage of the developed system is that the trapping solution was continuously pumped through the capillary by a means of pump with an efficiency flow rate controlled at 0.01ml min-1.
Keywords: determination, nitrogen dioxide, droplet method, atmosphere
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