Capillary Electrophoresis - Related Techniques

Related Techniques

As discussed above, separations in a capillary electrophoresis system are typically dependent on the analytes having different electrophoretic mobilities. However, some classes of analyte cannot be separated by this effect because they are neutral (uncharged) or because they may not differ significantly in electrophoretic mobility. However, there are several techniques that can help separate such analytes with a capillary electrophoresis system. Adding a surfactant to the electrolyte can facilitate the separation of neutral compounds by micellar electrokinetic chromatography. Charged polymers such as DNA can be separated by filling the capillary with a gel matrix that retards longer strands more than shorter strands. This is called capillary gel electrophoresis. This is a high-resolution alternative to slab gel electrophoresis. Some capillary electrophoresis systems can also be used for microscale liquid chromatography or capillary electrochromatography. A capillary electrophoresis system can also be used for isotachophoresis, isoelectric focusing, and affinity electrophoresis. In the case of amino acid separations, the ion charge ranges from -1 to -3 electrons but the size of the amino acid is dominated by the dye label; therefore changes in charge have a significant effect on mobility relative to changes in size.