Fluorometric determination of nitrogen dioxide in atmosphere sampled by the liquid droplet technique

A new, simple, sensitive and selective fluorometric method for the determination of nitrite has been developed. The reaction of nitrite with hydralazine in acidic medium, heated on a boiling water-bath for 15 min, produced a tetrazolo (5,1-a) phthalazine (Tetra-P). The product formed was measured at lambda(ex) = 274 nm and lambda(em) 345 nm. The fluorescence intensity was valid over a nitrite concentration range 0.067-60.3 no mL(-1), with a detection limit of 0.0091 ng mL(-1). The reproducibility of the proposed method was determined by running a different concentration of nitrite, 13.4, 33.5, and 46.9 ng mL(-1). The % recoveries and the relative standard deviations were found to be 100.6 +/- 0.9, 99.9 +/- 0.5, and 99.4 +/- 1.1%, respectively. The proposed method was applied successfully to the determination of nitrogen dioxide sampled from the atmosphere using the liquid droplet method. The nitrogen dioxide our wind tunnel was controlled by an NOx, analyzer based on a chemiluminescence analyzer detector (CLAD 1000). A linear graph was obtained for the nitrogen dioxide in the wind tunnel vs. NO, sampled by the liquid droplet method. The effect of interference substances in the determination showed that cations and anions did not disturb the process. The results obtained were satisfactory when compared with the reference method.