1992 Volume 8 Issue 2 Pages 207-211
Trace amounts of chlorine dioxide in water were detected by a fluorophotometric method that was based on the quenching of fluorescence of Chromotropic acid (CA). The interference by various ions in the determination was examined. In addition, the mechanism of the quenching of fluorescence was studied. Chlorine dioxide reacted with CA at a stoichiometric ratio of 1:1 at pH 3. Moreover, the quenching constant of the reaction system, suggested that the quenching of the fluorescence is dynamic. A linear relationship was found between the fluorescence intensity and the amount of chlorine dioxide in water over a range from 0.55ppb to 1.4ppm. The reaction of CA with chlorine dioxide was not influenced very much by metal ions, such as sodium, potassium, magnesium, zinc, lead, cupric and manganese ions, nor by the sulfurous ion. The limit of detection was 0.55 ppb, a value that corresponds to the amount of 3σ from the blank level.
