Separation of anilines by capillary electrophoresis with small ionic compounds as buffer additives

Addition of either ethanesulfonic acid or protonated triethylamine to the b ackground electrolyte was found to markedly improve the separation of proto nated anilines by capillary electrophoresis. These additives appear to form a thin coating on the capillary surface via a dynamic equilibrium. This re sults in a change in electroosmotic flow and reduces interactions of the sa mple cations with the silica surface. A mixture of 10 substituted anilines could be separated, including several positional isomers. Migration times o f the sample cations were reproducible with a RSD less than 1.0%. (C) 1999 Elsevier Science B.V. All rights reserved.