Gadolinium(III)in vivo speciation. Part 1. A potentiometric and spectroscopic study of gadolinium(III) citrate complexes

Abstract

Gadolinium(III) complexes of citric (3-carboxy-3-hydroxypentane-1,5-dioic) and 3-carboxypentane-1,5-dioic acid have been studied potentiometrically at 25°C and an ionic strength of 0.15 mol dm^–3 NaCl. Both [GdL](H₃L = citric acid) and [GdL(OH)]^– were detected. From potentiometric and spectroscopic evidence citrate is postulated to co-ordinate via the hydroxyl group and two carboxylate groups. The formation of the [GdL(OH)]^– species results from loss of the hydroxyl proton rather than co-ordination of hydroxide.