Abstract: STUDIES ON URANYL DECORPORATION BY MIXTUKES OF 2，3-DIHYDROXY-5-CARBO-METHOXYBENZYL AMINOCARBOXYLIC ACID AMIDE AND EDTAWANG YONGWEI；YAN QINGYU；XIE YUYUAN（Shanghai Institute of Materia Medica, Academia Sinica, 200031）ABSTRACT The ternary complexations of uranyl with six 2．3-dihydroxy-5-carbo-methoxybenzylaminocarboxylic acid amide chelating agents and ethylene diamine tetraacetic acid（EDTA） areinvestigated by potentiometric titration at 25℃ and an ionic strength of 0．1mol／l KNO_3. Compo-sitions and formation constants of the mixed ligand chelates are calculated using SCOGS2 pro-gram. The stabilities of mixed ligand chelates are compared． EDTA is likely to coordinate touranyl in EDDA forrn，Computer simulation shows that the decorporation in high uranyl concen-tration using mixtures of chelating agents may be possible. Kev words pH potentiometric Uranyl Catechol aminocarboxylic acid amide EDTA Synergistic decorporation