ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Photometric microtitrations. 9. Direct and successive chelatometric determination of scandium and lanthanoids in micromolar solutions using Xylenol Orange

V. Mach, S. Kotrlý, and K. Vytřas

Department of Analytical Chemistry, Institute of Chemical Technology, CS-53210 Pardubice

Abstract: Microgram amounts of scandium (chloroacetate buffer, pH = 2.4—3.4, λ = 540 nm) and erbium (acetate buffer, pH = 4.6—5.6, λ = 560 nm) can be  determined precisely with a very dilute titrant, c(EDTA) > 1 x 10^-4 mol dm^-3, owing to the sensitive colour transition of Xylenol Orange. The relative standard deviations and systematic errors are smaller than 1 % for the two metals if they are titrated separately. In a successive titration first scandium is determined at pH about 2.3 and λ = 540 nm and then, after adjusting the pH value to « 5 with acetate, erbium is titrated at λ = 560 nm. An adequate precision has been achieved for mixtures of the two metals (c(Er³⁺)/c(Sc³⁺) = = 0.6 to 4.6); however, the end-points are liable to certain systematic deviations in the range of micromolar concentrations.

Full paper in Portable Document Format: 433a377.pdf

Chemical Papers 43 (3) 377–387 (1989)