Determination of cadmium, copper, lead and zinc in water samples by flame atomic absorption spectrometry after cloud point extraction

Cloud point extraction (CPE) has been used for the simultaneous pre-concent ration of cadmium, copper, lead and zinc after the formation of a complex w ith 1-(2-thiazolylazo)-2-naphthol (TAN), and later analysis by flame atomic absorption spectrometry (FAAS) using octylphenoxypolyethoxyethanol (Triton X-114) as surfactant. The chemical variables affecting the separation phas e and the viscosity affecting the detection process were optimized. At pH 8 .6, pre-concentration of only 50 ml of sample in the presence of 0.05% Trit on X-114 and 2 x 10(-5) mol 1(-1) TAN permitted the detection of 0.099, 0.2 7, 1.1 and 0.095 ng ml(-1) cadmium, copper, lead and zinc, respectively. Th e enhancement factors were 57.7, 64.3, 55.6 and 63.7 for cadmium, copper, l ead and zinc, respectively. The proposed method has been applied to the det ermination of cadmium, copper, lead and zinc in water samples and a standar d reference material (SRM). (C) 2001 Elsevier Science B.V. All rights reser ved.