Highly selective spectrophotometric determination of chlorine dioxide in water using Rhodamine B

A method for the spectrophotometric determination of chlorine dioxide in the presence of other chlorine species, viz., free chlorine, hypochlorite, chlorite, chloramine and chlorate, was developed. The detection limit is 0.04 mg l–1 of chlorine dioxide; the calibration graph is linear over the range 0–1.5 mg l–1 of chlorine dioxide. The results show that free chlorine concentrations up to 40 mg l–1 and excess of oxychlorine species could be tolerated without interference, the method is rapid, sensitive and highly selective.