Capillary Electrophoresis (CE)

Source: Laboratory of Dr. B. Jill Venton - University of Virginia

Capillary electrophoresis (CE) is a separation technique that separates molecules in an electric field according to size and charge. CE is performed in a small glass tube called a capillary that is filled with an electrolyte solution. Analytes are separated due to differences in electrophoretic mobility, which varies with charge, solvent viscosity, and size. Traditional electrophoresis in gels is limited in the amount of voltage that can be applied because Joule heating effects will ruin the gel and the separation. Capillaries have a large surface area-to-volume ratio and thus dissipate heat better. Therefore, the voltages applied for a capillary electrophoresis experiment are quite large, often 10,000–20,000 V.

Capillary electrophoresis is useful for high-performance separations. Compared to liquid chromatography, CE separations are often faster and more efficient. However, capillary electrophoresis works best to separate charged molecules, which is not a limitation of liquid chromatography. CE has a greater peak capacity than high-performance liquid chromatography (HPLC), meaning the separations are more efficient and more peaks can be detected. The instrumentation can be very simple. However, HPLC is more versatile and many stationary and mobile phases have been developed for different types of molecules.