Abstract:

Due to the electric characteristics of the solute transport in capillary electrochromatography (CEC), some special phenomena might occur. An example is the peak compression effect in ion-exchange capillary electrochromatography, which cannot be explained with common chromatography theory. According to the basic model of relaxation theory, it is considered that there are “co-” and “counter-” solute flows in mobile phase and in stationary phase, the expressions of the first moment and the second center moment of profile, and column efficiency are derived by the method of Laplace transform. The relations of electrophoresis velocity, electroosmosis velocity and electric dispersion velocity are also investigated with these expressions. The results show that this new model offers a better explanation for peak compression effect on the migration behaviour of charged solute in CEC. The retention time will be shorter by peak compression effect, which is similar to a solvent gradients process. The peak compression effect is not steady, and doesn’t appear until the conditions are fitted in some special situation.

Key words: peak compression, relaxation theory

, ion-exchange capillary electrochromatography