(95%) with at least 15 mg 2-HIYPMI. On this basis, studies were carried out at 2-HIYPMI concentration of 15. This concentration of ligand is enough for the separation-preconcentration procedure because of the very low level of the investigated metal ion concentrations in real samples. Probably at ligand amount higher than 15 mg, due to possible formation of charged unretainable species, the amount of recovery will be reduced significantly. 15 mg of 2- HIYPMI was chosen to account for other extractable species that might potentially interference with the assaying of metal ions.