The Theory for Zone Migration in Electrochromatography

In electrochromatography, both a mobile phase and an electrical current pass through a column containing a stationary phase. Therefore, charged eluites migrate through the column due to an electrophoretic and a chromatographic transport mechanism. In this paper, the mass balance equation for finite concentration differences is solved for charged eluites. Numerical examples are shown to illustrate the physical consequences of the obtained solution of the mass balance equation. The solution contains chromatographic and electrophoretic zone migration theory as limiting cases. In the general case, the mixing of chromatographic and electrophoretic transport mechanisms gives rise to strong nonlinear effects. These effects may cause strong band broadening or, alternatively, a stabilized zone which does not change its form during the migration through the column.