Cloud point extraction with mixed micelles of TX-114/DOSS and derivative spectrophotometry for simultaneous determination of Fe2+ and Co2+ using 2,2′,6',2"-terpyridine

A new cloud point extraction procedure with derivative spectrophotometry for the simultaneous preconcentration and determination of Fe2+ and Co2+ has been developed. In this method both the Fe2+ and Co2+ metal ions are simultaneously complexed with 2,2',6',2"-terpyridine at a pH of 3.8. The complexes of Fe2+ and Co2+ are then extracted into mixed micelles of surfactants (Triton X-114 and docusate sodium salt). Various parameters such as pH, concentration of the ligand, concentrations of the surfactant, concentration of salt (Na2SO4), equilibration temperature and time have been optimized. Under optimum conditions, the linear ranges of Fe2+ and Co2+ are found to be 0.373-2.42 mu g mL(-1) and 3.14-18.86 mu g mL(-1) respectively. Their corresponding limits of detections are found to be 0.498 ng mL(-1) and 4.54 ng mL(-1). The proposed method has been successfully applied to the determination of Fe2+ and Co2+ in tap water and sea water. The recoveries were found to be in the range of 98-107%.