Complexation ion chromatography —an overview of developments and trends in trace metal analysis

Complexation ion chromatography (IC), including all ion chromatographic modes in which complexation is exploited for the separation and detection of metal ions in different ways, is now a widely accepted method of trace metal analysis. Some of the significant advances in the theoretical aspects and practical applications of complexation IC modifications (non-suppressed cation chromatography with complex- forming mobile phases, coordination chromatography with chelate-forming bonded phases, ion-exchange and ion-pair chromatography of anionic metal chelates) recently developed in the authors' laboratories are reviewed. The retention behaviour and separation mechanism of non-complexed and completed metal analytes are discussed from the point of view of basic coordination chemistry (stability of metal complexes, effective charge of metal atom, ligand completing ability, etc.). Comparisons and contrasts between various metal complexation IC techniques and their common features and advantages relative to other methods used in analyses for transition and heavy metal ions are evaluated.