High-performance chelation ion chromatography of transition and heavy metal ions on polystyrene-divinylbenzene resin dynamically modified with 4-chlorodipicolinic acid

A neutral polystyrene-divinylbenzene column, combined with 4-chlorodipicoli nic acid present in the mobile phase, has been developed as a chromatograph ic system for the high efficiency isocratic separation of transition and he avy metal ions. Retention arises from the formation of a stable dynamically coated chelating stationary phase, the capacity of which is dependent upon both the pH and ligand concentration in the eluent. The results obtained i llustrate the increased loading and selectivity of this chlorinated chelati ng molecule in comparison with unsubstituted dipicolinic acid, exemplified by the separation of 7 metals in under 8 min. The column also displayed a s trong affinity for Cd-II and an unusual retention for Ni-II, which showed a good symmetrical peak shape.