Andrei V. Bordunov

Adjustable-capacity anion-exchange separator

A cryptand-based anion exchanger has been developed in which the capacity and to a lesser degree, selectivity are adjustable simply by the choice of the mobile phase. Although much work has been done in the past using cryptand-based anion exchangers, these stationary phases were based on adsorbed cryptands rather than covalently bound cryptands. These phases suffered from the usual problems associated with adsorbed systems. A novel styrene-based cryptand has been synthesized which can be covalently attached to a solid support. A brief review of cryptands and binding constants as well as comparisons of adsorbed phases versus covalently bound phases will be discussed. Some of the unique chromatographic properties of this prototype column will be illustrated as well.

Environmental applications of a cryptand adjustable-capacity anion-exchange separator.

A 2.2.2 cryptand-based anion exchanger was recently introduced as a commercial product. This new technology relies on a covalently bonded 2.2.2 cryptand, which allows one to selectively control the capacity of the column simply by the choice of eluent. This provides the analyst with more flexibility over conventional anion exchangers to suit the needs of the sample matrix. Since that time, a 2.2.1 version has also been developed and studied. In this paper we will compare the two types of columns and choose the best one for analyzing several environmental samples.