Capillary Electrophoresis Apparatus

A diagrammatic representation of a capillary electrophoresis instrument is shown in figure 17. Essentially it consists of two buffer vessels connected by a length of silica capillary tubing dipping under the surface of each. An electrode is situated in each buffer vessel and one acts as the cathode and the other the anode; both electrodes are connected to a high voltage supply. A third buffer vessel is available that contains the sample from which the substances of interest are placed in the beginning of the silica tube by an electrophoretic migration. The front of the capillary tube is first dipped into the sample vessel and the power turned on, driving a group of the charged particles by electrophoretic migration into the end of the capillary tube. The tube is then removed from the sample vessel and placed back into the anode buffer vessel and electrophoresis continued. The individual charged particles are driven differentially along the tube by electrophoretic migration and all the solute driven in the same direction by osmosis. Just prior to the cathode a detecting system is inserted into the silica capillary and this detector monitors the passage of the solutes passing through the capillary at that point.

Figure 17. Capillary Electrophoresis Apparatus

The detector may take several forms as described below and the output is fed to a suitable computer and the data processed and displayed on a chart or printer.