A method for the preconcentration of Cu(II) by cloud point extraction (CPE) followed by its determination using neutron activation
analysis (NAA) was developed. The method involves the use of a nonionic surfactant, namely PONPE-7.5, and a chelating agent
1-(2-pyridylazo)-2-naphthol (PAN). The phase diagram of the surfactant was constructed and the effects of different additives
on the cloud point were investigated. Factors, such as the solution pH, ionic strength, temperature, and concentrations of
chelating agent and surfactant, which can influence the extraction efficiency of the metal, were optimized. The copper(II)
chelate was extracted into a surfactant-rich phase of small volume with a recovery of nearly 100% and a preconcentration factor
of 60. The small volume of the surfactant-rich phase obtained complies with the green chemistry concept, allowing the design
of extraction procedures having lower toxicity than those using organic solvents. The method was applied to tap water samples.