A simple and practical preconcentration method using ultrasound-assisted cloud point extraction for determination of Cu (II) in various water samples has been developed. 2-mercaptopyrdin-n-oxide as a complexing agent and Triton X-114 as a surfactant are used in proposed method. After phase separation, the surfactant-rich phase is diluted with methanolic nitric acid and determined by flame atomic absorption spectroscopy. The variables parameters affecting the complexation and extraction steps are optimized. Under optimum conditions, the detection limit of 2.2 ng mL-1 is obtained for Cu (II) ions. The method is successfully applied to the determination of Cu (II) in drinking and mineral water samples.
