Fluorometric Determination of Aluminium(III) and Cadmium(II) by Solvent Extraction of the Ternary Complex Composed of Metal Ion, 8-Hydroxy-5-quinolinesulfonic Acid, and Methyltrioctylammonium Ion

Abstract

Abstract A fluorometric micro determination of aluminium(III) and cadmium(II) using the formation of metal–8-hydroxy-5-quinolinesulfonic acid–capriquat (methyltrioctylammonium) ternary complex is described. These complexes are easily extracted into chloroform phase and the extract emits a strong fluorescence. Spectra of aluminium(III) and cadmium(II) ternary complexes have the excitation maximum at 396 nm and 400 nm, and emission maximum at 501 nm and 524 nm, respectively. Fluorescence intensity of the aluminium(III) and cadmium(II) ternary complexes extracted into chloroform showed the constant and maximum values in the pH range of aqueous phase from 5.3 to 8.5 and 8.1 to 8.5, respectively. The calibration curves for aluminium(III) and cadmium(II) show good proportionality in the concentration range from 0.5 to 5.0 and 1.0 to 50.0 μg, respectively. The relative standard deviation observed with four measurements was found to be 1.8% for 0.5 μg of aluminium(III) and 1.1% for 10.0 μg of cadmium(II). The effect of diverse ions is studied and a 25-fold amount of Cu(II), Ni(II), Fe(II), Fe(III) in weight gave errors, however, the interferences were easily eliminated by the addition of appropriate masking agent. In the determination of cadmium(II), an equal amount of Co(II), Ni(II), Mn(II), Fe(III) and twice amount of Al(III) gave negative errors, however, the interference of Fe(III) and Al(III) were also eliminated as above.