Spectrophotometric determination of copper in pharmaceutical, food and environmental samples using some ligands

In this work, two different ligands, 3,3,-[l,3-propanediyldiimine)-bis(3-methyl-2- butanone]dioxime (PnAO) and S,S'-bis(2-aminophenyl)oxalate (H2L), have been investigated for the analytical use of extraction of copper from pharmaceuticals, foods and environmental samples. The direct spectrophotometric determination of copper(II) in aqueous media has been feasible using PnAO ligand. However, the extraction using this ligand is not possible in common organic solvents since the PnAO-Cu(II) complex formed is extremely soluble in water, and the complex possesses very high ionic character. The extraction using the other ligand H2L, on the contrary, was successful using chloroform in aqueous media. The amount of copper(II) in the organic phase was quantified by visible spectrophotometry. The results have shown that the concentration ranges for copper(II) ions using PnAO and H2L are within 0.5-350 mg/mL and 0.4-150 mg/mL, respectively. The effect of diverse ions on the spectrophotometric copper(H) determination was investigated for both ligands and maximum error was within limits (±2%). The results obtained using both ligands were highly compatible with each other. The spectrophotometric copper(II) determination using PnAO is very practical, not time-consuming, and could be applied to wide concentration range although extraction method using H2L was found to be more advantageous than the method using PnAO from the point of the effect of diverse ions, selectivity, specificity for copper(H). Key words : Spectrophotometric determination of copper, extraction, complexation, preconcentration, diverse ion effects VI