Determination of Lanthanide (III) Ions by Using a Flotation - Spectrophotometric Method

Abstract

This paper reports our attempt at determining Ln (III) ions by using a flotation-spectrophotometric method and our findings. When a ternary ion-association complex of Ln (III) coordinated by thiocyanate (SCN⁻) and diantipyryl methane (DA[Mdot]) is separated by a mixed solvent containing benzene and chloroform at pH 3.1 – 4.2, a third phase is observed between the aqueous and organic phases. The solid ternary complex can be dissolved in acetone that contains thenoyltrifluoroacetone (TTA). The individual Ln (III) ion can be determined by using the 4th derivative spectra directly. The equilibrium constant of the ternary composition ratio of Ln(II1) to ligand is estimated by the equilibrium shift method. The mole ratio of Ln(II1) to DAM and to SCN⁻ is 1:3 each. The composition of the tcrnary complex seems to be Ln(III):DAM:SCN⁻=1:3:3.

Key Words:

• Flotation - Spectrophotometric method
• Third Phase
• f-f transition
• Dcrivation Spectra