Atomic-Absorption Determination of Copper(II) in Water Samples after Its Cloud-Point Extraction Preconcentration

We study and optimize the conditions for the cloud-point extraction (CPE) preconcentration of Cu(II) in the form of its complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyrylium chloride in the micellar phase of the nonionic surfactant Triton X-100. The introduction of ammonium benzoate into the system until a pH of 4.5 is reached at a Triton X-100 concentration of 0.4 vol % leads to the initiation of the formation of a micellar phase at room temperature. We develop a procedure for the atomic absorption determination of Cu(II) after its CPE preconcentration. The calibration dependence is linear in the concentration range of 5.0 to 213 mu g/L, and the detection (c(min)) and determination (c(lim)) limits are, respectively, 1.5 and 5.0 mu g/L. The proposed procedure is tested in the analysis of natural and drinking waters, and the relative standard deviation (RSD) does not exceed 4%.