Interaction of scandium, yttrium, lanthanum and cerium (3) with pyrocatechol violet

Scandium, yttrium, lanthanum and cerium (3) complexing with pyrocatechol violet is studied. All these elements form complexes of the 1:1 composition. The values of λmax, pH and ε for these element complexes are: 585-590 nm, 5.6-6.0 (2.05±0.05)x104 (Sc3+); 600 nm, 7.4-7.6 (2.07±0.05)x104 (Y3+); 600 nm, 7.4-7.6 (1.22±0.03)x104 (La3+); 600 nm, 7.4-7.6 (1.30±0.03)x104 (Ce3+). Scandium reaction with pyrocatechol violet showed that scandium interacts in the form of Sc3+ ion, and reagent - in H3R- form. The Berr law in respect to scandium and ittrium is observed, as to lanthanum and cerium it is not observed