Cloud point extraction and flame atomic absorption spectrometric determination for copper(II) ion in environmental samples

A cloud point extraction procedure for the preconcentration of Cu(II) ion in environmental samples is presented. After complexation with 7-iodo-8-hydroxyquinoline-5-sulfonic acid, the analyte was quantitatively extracted from the phase rich in the surfactant alkylphenol polyoxyethylene, concentrated, and determined by flame atomic absorption spectrometry. Parameters that affect extraction efficiency, such as solution pH, concentrations of 7-iodo-8-hydroxyquinoline-5-sulfonic acid and alkylphenol polyoxyethylene, and equilibration temperature and time, were investigated. Under optimum conditions, the proposed procedure facilitated the determination of Cu(II) with a detection limit of 0.6 ng mL(-1) and a relative standard deviation (n = 7) of 1.9 %. The method was applied to Cu(II) determination in tap water and a certified reference material (GBW 08301, river sediment) with satisfactory results.