The present study characterizes a new polymeric ligand exchanger (PLE) for enhanced separation of trace anionic ligands, and investigates related interfacial chemistry. Compared to conventional anion exchangers, the PLE exhibited significantly different selectivity sequence and elution profiles, which may be utilized in enhancing selective capture of target solutes and/or chromatographic separation of anionic ligands. Experimental data indicate that the exchanger phase pH is significantly higher across the resin-solution interface caused by the Donnan co-ion exclusion effect. Intraparticle diffusion appears to be the rate-limiting step during a typical fixed-bed column run. A linear free-energy relationship (LFER) was derived and experimentally validated between the binary separation factors and the aqueous phase metal-ligand stability constants.