Spectrophotometric study of the complexation equilibria of lanthanum(III) with 1,4-bis(4′-methylanilino)anthraquinone and the determination of lanthanum(III)

Abstract

The complexation equilibria of lanthanum(III) with 1,4-bis(4′-methylanilino)anthraquinone (Quinizarin Green) were studied spectrophotometrically in 40%V/V dimethylformamide using graphical analysis of the absorbance curves. The reaction mechanism of lanthanum with the bisarylaminoanthraquinone dye within the pH range 6–9.25 was demonstrated. The thermodynamic stabilities and the molar absorptivities of the complexes formed were determined. The optimum conditions for the spectrophotometric determination of La(III) with this reagent were found.