Multivalent weak electrolytes - risky background electrolytes for capillary zone electrophoresis

Multivalent weak acids and bases are useful components of buffers in electrophoresis. The use of such buffers as background electrolytes (BGEs) in capillary zone electrophoresis (CZE) is, however, risky due to the existence of unsafe regions in the anal. window of the sepn. This contribution discusses the problems and shows that multivalent weak species in BGEs bring about the same effects as mixts. of two independent co-ions, i.e., the presence of two centers of symmetry in the electropherograms and the existence of a migrating system zone with a mobility in between these two centers of symmetry. The system zone deteriorates the anal. sepn. and detection of the analytes in its neighborhood. Illustrative exptl. examples for both cationic and anionic CZE are shown and related discussion is given. Finally, some basic rules are formulated to avoid the prepn. of risky BGEs. [on SciFinder (R)