Within this work the analysis of the kinetic stability of a series of yttrium complexes, i.e., Y-citrate, Y-NTA, Y-CDTA as
well as Y-humic acid (Y-HA) has been successfully performed by the free-ion selective radiotracer extraction (FISRE) method.
FISRE uses 90Y with a high specific activity to perform CHELEX extractions in a buffered aqueous solution at pH 6 in two different modes
by monitoring the dissociation and association reactions of the corresponding complexes. Whereas in the case of Y-citrate
the dissociation profile could be successfully described in terms of (pseudo) first order kinetics, the other complexes tend
to form two species with different kinetic properties, although only one species is predicted by speciation calculations.
In the batch FISRE method, all (except Y-NTA) corresponding association rate constants were determined by monitoring the formation
rate of the yttrium complexes.