STUDIES ON THE RETENTION BEHAVIOR OF METAL-EDTA COMPLEXES IN CATION CHROMATOGRAPHY

Separation of metal-EDTA complexes (e.g. with Cu2+, Ni2+ and Pb2+) has been carried out with a cation-exchange polymer based column. Two mob ile-phase systems, containing either nitric or perchloric acid, have b een studied and the metal complexes with EDTA have been detected by UV spectrophotometry. A retention model has been developed. It takes int o account both ion-exchange and adsorption phenomena of all positive, neutral and, as an attempt, negative metal-EDTA species. The ion-excha nge behaviour of the metal-EDTA complexes and the adsorption effects d ue to neutral species have been applied for an on-line preconcentratio n procedure.