Capillary Electrophoresis

Abstract

Capillary electrophoresis is an electric field‐mediated microseparation technique that utilises narrow‐bore fused‐silica capillaries (10–100 μm) and high applied electric fields (100–1000 V/cm) enabling short analysis times with high separation efficiency and excellent resolution, whereas the narrow bore capillary readily dissipates the generated Joule heat. The main separation modes of capillary electrophoresis are capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), capillary isoelectric focusing (cIEF), capillary gel electrophoresis (CGE) and capillary electrochromatography (CEC). As a truly orthogonal method to high‐performance liquid chromatography (HPLC), capillary electrophoresis is recently gaining high importance in the pharmaceutical, biotechnology and biomedical industries, especially for the analysis of protein therapeutics.

Key Concepts:

  • Capillary electrophoresis (CE) is a truly orthogonal separation method to chromatography‐based techniques.

  • CE is a fully automated approach to electrophoresis.

  • The narrow bore capillaries used in CE enable application of high separation voltages without significant heat generation.

  • Electroendoosmotic flow (EOF) generates a bulk fluid flow within the narrow bore capillary and therefore one of the driving forces of CE analysis.

  • The main separation modes of CE are: Capillary zone electrophoresis (CZE) separation is based on free solution mobility; micellar electrokinetic chromatography (MEKC) utilises partitioning of hydrophobic analytes within charged micelles; capillary gel electrophoresis (CGE) applies sieving polymers for size separation of macromolecules; and capillary isoelectric focusing (cIEF) separates amphoteric analytes based on their charge states; and capillary electrochromatography (CEC) based on the interplay between electric field and chromatography‐mediated separations.

  • CE is one of the emerging separation techniques in the biotechnology, biopharmaceutical and biomedical industries.

  • Microfluidics devices integrate the concept of CE with fluidics sample manipulation such as on chip sample preparation.

Keywords: Separation; electrophoresis; miniaturisation; micellar electrokinetic chromatography; capillary electrochromatography; gel electrophoresis; biopolymer analysis

Figure 1.

Block diagram of a typical capillary electrophoresis system. The ends of the capillary are immersed in small vials containing the background electrolyte and two platinum wires connected to a high‐voltage power supply capable of delivering up to 30 kV electric potential. The detection system is placed close to the outlet end of the capillary and can be either a UV/visible light absorbance (provided either with filters or monochromator) or a diode‐array detector. Some instruments are provided with a laser‐induced fluorescence detector. A sample tray for sample loading and the computer controlling the entire unit are not shown.

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References

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Further Reading

Breadmore MC, Dawod M and Quirino JP (2011) Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2008–2010). Electrophoresis 32: 127–148.

El Deeb S, Iriban MA and Gust R (2011) MEKC as a powerful growing analytical technique. Electrophoresis 32(1): 166–183.

El Rassi Z (2010) Electrophoretic and electrochromatographic separation of proteins in capillaries: an update covering 2007–2009. Electrophoresis 31(1): 174–191.

Haselberg R, de Jong GJ and Somsen GW (2011) Capillary electrophoresis‐mass spectrometry for the analysis of intact proteins 2007–2010. Electrophoresis 32(1): 66–82.

Journal of Chromatography (1989) First International Symposium on High‐Performance Capillary Electrophoresis. Boston, MA, April 10–12, 1989. Journal of Chromatography 480: 1–435. [The entire history and developments of CZE can be followed in a series of special issues of the Journal of Chromatography, dedicated to the proceedings of meetings on high‐performance capillary electrophoresis, the first of which took place in Boston in April 1989.]

Kleparnik K and Bocek P (2010) Electrophoresis today and tomorrow: helping biologists’ dreams come true. BioEssays 32(3): 218–226.

Proceedings of the 22nd International Symposium on Microscale Bioseparations and Methods for Systems Biology. 9–13 March 2008. Berlin, Germany. Journal of Chromatography A 1206(1): 1–88.

Righetti PG (1996) Capillary Electrophoresis in Analytical Biotechnology. Boca Raton, FL: CRC Press [An excellent book to overview the advances of the field].

Terabe S (2009) Capillary separation: micellar electrokinetic chromatography. Annual Review of Analysis of Chemistry (Palo Alto, California) 2: 99–120.

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How to Cite close
Righetti, Pier Giorgio, and Guttman, András(Jul 2012) Capillary Electrophoresis. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002680.pub2]