alte Seiten

Capillary electrophoresis (CE) is a widely employed separation technique and known as an orthogonal method to HPLC. Miniaturized CE (CE on chip) has proven the predictions of the scaling laws. For separations in preparative scale, free-flow electrophoresis is more suited due to its continuous operation mode. While in CE the electric field is applied along the capillary in FFE the electric field is applied perpendicular to a hydrodynamic flow through a separation compartment. Thus, all analyte molecules are affected by two velocity vectors (electrophoretic and hydrodynamic velocity) leading to a sum vector which is at an angle to the hydrodynamic flow. This results in a geometrically two-dimensional separation since the time domain is transformed into a spatial domain. Several separation modes known from CE like zone electrophoresis, isotachophoresis, or isoelectric focusing can be implemented in FFE. Also the use of a miniaturized FFE (µFFE) device has affirmed the validity of the scaling laws.