Visualizing ion electromigration during isotachophoretic separations with capillary isotachophoresis-NMR

Sample stacking techniques in electrophoresis are gaining popularity due to their ability to provide improved sensitivity and separation efficiency. The principles behind sample stacking and electrophoretic migration have been studied extensively. Nevertheless, there are still a number of observations and descriptions of ionic boundaries and migration modes for which the underlying principles are not yet fully understood. For example, the behavior of capillary isotachophoresis (cITP) systems that exhibit self-sharpening effects can be complex, especially when the buffer systems contain many ionic components. In this work, cITP coupled with H-1 NMR detection is used to study electrophoretic migration of ions in both anionic and cationic cITP. A significant advantage of H-1 NMR over other detection methods is the high specificity of this method, allowing detection of individual buffer and analyte constituents within the migration zones.