Application of cloud point extraction technique to preconcentration and spectrophotometric determination of free chlorine in water samples

A rapid, selective, and sensitive cloud point extraction process using mixed micelle of a nonionic surfactant Triton X-114 and an anionic surfactant, SDS, to extract chlorine from aqueous solution was investigated. The method is based on the color reaction of chlorine with N,N-diethyl-p-phenylenediamine (DPD) in phosphate buffer media and cloud point extraction of the produced dye. Various factors and extraction and reaction conditions such as surfactant concentration and reagent concentration were studied and the analytical characteristics of the method (e.g. limit of detection, linear range, preconcentration, and improvement factors) were obtained. Linearity was obeyed in the range of 3.0–450 ng/mL of chlorine and the detection limit of the method was 1.0 ng/mL. The interference effects of some cations and anions were also tested. The proposed method was successfully applied to the determination of free chlorine in drinking, river, well and pool swimming water samples.