Separated components are quickly identified by online detectors during the analysis, in contrast to the time-consuming staining steps required for gel separations. With only nanoliter sample volumes required for analysis, CE's speed, sensitivity, and versatility make it an attractive separation technique for many scientists. A typical capillary electrophoresis system consists of a fused-silica capillary, with an inside diameter ranging from 25 to 75 mm, that connects two buffer reservoirs, a power supply, and a detector. Molecules are separated as an electrical force drives them at different rates through the capillary filled with electrolyte. A variety of buffers and additives are used to enhance separations.
Separation occurs as solutes migrate in discrete zones and at different velocities.
The separated sample components are monitored by a detector as they travel through a segment of the capillary, and the detector signal is displayed as peaks on an electropherogram, similar to a chromatogram. With several operating modes available, a single instrument, often a single capillary, can be used for the practical separation of many different classes of compounds. Although biochemists are generally conservative in accepting new techniques, the potential for this particular one appears enormous, based on the number of users and their applications, he notes. According to Novotny, the three major types of biomolecules currently being examined with CE are proteins, nucleic acids, and carbohydrates. The last is emerging more slowly as an application area for CE because most glycoconjugate samples still require some form of pretreatment.