Retention Mechanism and Chelation Theory
The retention mechanism of various complexation and chelating ion exchange stationary phases is considered. Special attention is devoted to the conditions under which chelation within the stationary phase becomes the dominant factor governing the selectivity exhibited for metal ions. Suppression of electrostatic interactions between solvated metal cations and charged functional groups can be achieved through the precise control of ionic strength, via the addition of strong electrolyte to the mobile phase and by variation of the column temperature. How these various factors affect the resultant efficiency and selectivity in HPCIC are considered within this Chapter.