Zwitterionic ion-exchangers in liquid chromatography

Zwitterionic ion-exchangers represent a new direction in the development of stationary phases for different modes of high-performance liquid chromatog raphy. The combination of positively and negatively charged sites in a sing le particle, or within the functional groups of a single molecule attached to the surface of an adsorbent, provides unique opportunities to vary the s electivity of separation. The classification of zwitterionic ion-exchangers based on their structure, distribution of oppositely charged groups, and t heir applications is considered.