New method for the flow injection spectrophotometric deternination of low concentration chlorine dioxide in water using methylene blue

A reverse flow injection spectrophometric method for the determination of chlorine dioxide was developed with leucomethylene blue as the coloration reagent. By this method low concentration chlorine dioxide in water was determined in the presence of Cl_2 and anion species such as ClO~-, ClO~-_2 and ClO~-_3. The linear range of ClO_2 measurement is 0~1.91 mg/L with a detection limit of 0.028 mg/L. The presence of chlorine and hypochlorite ion can be masked by using oxalic acid. Chlorate does not interfere with the measurement. The permissible maximum concentration of ClO~-_2 is 3.0 mg/L.