Determination of cobalt and nickel in water samples by flame atomic absorption spectrometry after cloud point extraction

Cloud point extraction has been used for the preconcentration of cobalt and nickel, after the formation of a complex with 1-(2-thiazolylazo)-2-naphtho l (TAN), and later analysis by flame atomic absorption spectrometry using o ctylphenoxypolyethoxyethanol (Triton X-114) as surfactant. The chemical var iables affecting the separation phase and the viscosity affecting the detec tion process were optimized. Under the optimum conditions, preconcentration of only 50 mi of sample in the presence of 0.05% Triton X-114 permitted th e detection of down to 0.24 mug l(-1) cobalt and 0.44 mug l(-1) nickel. The enhancement factors were 57 for cobalt and 65 for nickel. The proposed met hod has been applied to the determination of cobalt and nickel in water sam ples. (C) 2001 Elsevier Science B.V. All rights reserved.