Development of a Cloud-Point Extraction Method for Determination of Trace Amounts of Copper(II) in Water Samples

A simple and rapid cloud-point extraction method by using a Schiff base extractant, named bis(2hydroxynaphthaldehyde)-1,2-propanediimine, is presented for preconcentration of trace amounts of copper ions in water samples, prior to the determination by flame atomic absorption spectrometry. The process is based upon the complexation of Cu(II) ions by the Schiff base. The formed complexes are soluble in a micellar phase composed by the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114), and then are extracted into the surfactant-rich phase at above its cloud-point temperature. The effect of parameters influencing the extraction efficiency, such as aqueous solution pH, concentration of the Schiff base, amount of the surfactant, equilibration temperature and incubation time were investigated and discussed. Under the optimum experimental conditions, the calibration plot was linear in the range 1-400 mu g/L with a limit of detection 0.3 mu g/L. A preconcentration factor of 20 was achieved by the presented method. The proposed method was successfully applied for the determination of copper in various water samples.