| Abstract
| - Yttrium(III) equilibria in the presence of catecholamines adrenaline (AD), noradrenaline (NAD), and dopamine(DP) have been investigated by potentiometric titration in aqueous solution in I = 0.20 mol·dm-3 KCl ionicmedium and at 298.15 K. The complexation model for Y(III)−catecholamine systems has been established bythe “BEST” software from the potentiometric data. The types of complexes in the yttrium(III)−catecholaminesystems have been ascertained, and the protonation constants for catecholamines and the stability constants foryttrium(III) complexes with catecholamines have been obtained. The stability constants of YHL2+- and Y(HL)2+-type complexes are reported. Catecholamines can form stable yttrium(III) complexes with the phenolic hydroxylgroups of catecholamines as the binding site to yttrium(III). In terms of the ligands, the stability of complexesranks in an order such as dopamine > adrenaline > noradrenaline. The stability constants of Y(III)−adrenalinecomplexes are higher than their La(III) complexes due to the higher ionic potential of Y(III). The ionic radii ofCa(II) and Y(III) are roughly equal, but Y(III) has a higher charge than Ca(II). Therefore, Y(III)−catecholaminecomplexes are relatively more stable than Ca(II)−catecholamine complexes. This result may be utilized for invitro and in vivo studies.
|
