[en] It is shown that a mixed ligand chelate (MLC) is superior to that of the primary chelate alone for the decorporation of monomeric plutonium. Thus, EDTA plus Tiron reduces the level of Pu in the skeleton to about 40% less than that of EDTA alone when treatment was begun two hrs post ²³⁹Pu. However, DTPA alone was still superior to EDTA/Tiron under the given experimental conditions. However, this appears to be due to the rapid metabolic destruction of secondary chelants such as Tiron and similar bi-dentate derivatives of catechol and salicylates. Investigations are under way to improve such MLC's by the use of metabolic inhibitors to increase the plasma concentrations and residence times of the secondary chelants. In addition, MLC's consisting of metabolically stable chelants are undergoing testing. Therapy of cadmium poisoned mice by single and mixed chelants is also under study. A molar ratio of EDTA to Cd of 1.6 reduces the mortality by half of female mice given 5 min (i.p.) post supralethal doses of CdCl₂, while a molar ratio of 4.7 for 2, 3-dimercaptopropanol-1-sulfonate (DMPS) is required. No protection is observed with penicillamine (PA) or salicylates (SA) alone. However, combinations of EDTA with both PA and DMPS or SA and DMPS afford protection under conditions (30 min post Cd) where the individual chelants are ineffective. Automated potentiometric titrations are utilized to detect MLC formation and to evaluate their stability. The titration data are used as a screening procedure to ascertain whether a given chelant combination is worth testing in vivo