The interactions between oligonucleotides and inorganic cations have been measured by capillary zone electrophoresis. With increasing concentrations of divalent cations (Ca2+, Mg2+, Mn2+ and Ni2+) in the running buffer, the migration behavior was evaluated by calculation of the binding constants. Besides these fundamental studies of binding equilibria, different buffer components, tris(hydroxymethyl)aminomethane and 3-(N-morpholino)propanesulfonic acid, have been investigated and their effects on metal ion binding quantifie