药物分析学报

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Surfactant Assisted Separation Spectrophotometric Procedure for the Trace Analysis of Copper (II) in Drug and Water Samples Using a Heterocyclic Pyridyl Azo Dye

Magda A Akl, Magdy M Bekheit and Qasim Mezban Salih

4-(2-pyridyl-Azo) resorcinol mono sodium mono hydrate (NaPAR), a heterocyclic azo dye, was investigated for the flotation of copper (II). The metal ion forms a faint red complex with NaPAR in aqueous solution. An intense clear red layer was formed in the scum, after flotation, by adding an oleic acid (HOL) surfactant. The composition of the float is 1:2 (Cu(II): NaPAR). A highly selective and sensitive spectrophotometric procedure was proposed for the determination of micro-amounts of Cu(II) as its floated complex in the pH range 3.0-5.0. Beer’s law was obeyed up to 5x10-5 mol l-1. The Interferences from various foreign ions were avoided by adding excess NaPAR. The molar absorptivities of Cu-NaPAR and Cu-NaPAR-HOL systems are 5.3×104 and 6.1×105 mol-1cm-1 for the colored complexes in the aqueous and scum layers, respectively. The Cu-NaPAR complexes formed in aqueous solution and in the HOL were characterized by infrared spectral studies. The method was successfully applied to the analysis of Cu(II) in water and drug samples with a recovery >95% and a RSD <1.5%. The separation mechanism is explained.