Flow-Injection Chemiluminescence Sensor for the Determination of Free Chlorine in Tap Water

A novel chemiluminescence(CL) sensor combined with flow-injection analysis has been developed for determining free chlorine in tap water. The analytical reagent luminol was immobilized on an anion exchange resin column. While a volumn of sodium hydroxide passed through the column, luminol was eluted from the resin in alkaline aqueous solution and then mixed with a sample stream to react and produce CL. The CL emission intensity was correlated with the standard ClO− concentration in the range 1×10−8 to 4×10−5 g ml−1, and the detection limit was 8×10−9 g ml−1 ClO−. Interfering metal ions present in water were effectively separated by a pre-column cation exchanger. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of less than 5%. The sensor was stable for over 200 times and has been applied successfully to the determination of ClO− in tap water.