Cloud Point Extraction of Trace Amounts of Copper and Its Determination by Flow Injection Flame Atomic Absorption Spectrometry

A simple and convenient method based on cloud point extraction was proposed for the deter- mination of copper. The extraction was carried out in the presence of 2-[(2-mercaptophenylimino)-methyl]phenol (MPMP) as the chelating ligand and octylphenoxypolyethoxyethanol (Triton X-114) as the non-ionic surfactant. After phase separation, the surfactant rich phase containing the complex was diluted with 1.0 mol L–1 solution of HNO3 in methanol and the analyte concentration was determined by flow injection flame atomic absorption spectrometry. Under the optimum conditions, an enhancement factor of 81 was obtained for the preconcentration of copper with 25 mL sample solution. The calibration graph was linear in the range of 1–150 µg L–1, the relative standard deviation (RSD) for ten replicate determinations at 80 µg L–1 Cu level was 1.8 %, and the limit of detection (3 s) and quantification (10 s) were 0.15 and 0.50 μg L–1 respectively. The accuracy of method was confirmed by analysis of certified reference materials and recovery experiments. The proposed method was successfully applied to the determination of copper in rice flour and water samples. (doi: 10.5562/cca1803