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

A reverse flow injection spectrophotometric method for determination chlori ne dioxide was developed with leucomethylene blue as the coloration reagent . By this method low concentrations of chlorine dioxide in water were deter mined in the presence Of Cl-2 and anion species such as OCl-, ClO2- and ClO 3-. The linear range Of ClO2 measurement is 0-1.91 mg/L with a detection li mit of 0.02 mg/L. The presence of chlorine and hypochlorite ion can be mask ed by using oxalic acid. Chlorate does not interfere with the measurement. The permissible maximum concentration of ClO2- is 3.0 mg/L.