Capillary Zone Electrophoresis

 Capillary zone electrophoresis (CZE) is electrophoresis in very thin capillaries. It is an analytical separation method that is compatible with high field strength (200 to 800 V/cm) and small samples ) micrograms to nanograms). The high field strength makes the separation rapid and gives high resolving power (1). The very small capillary diameter, less than 0.2 mm, counteracts dispersion of the zone, presumably through interaction of the analyte with the inner wall of the capillary. The sample is detected by its absorbance or fluorescence as it proceeds past a stationary detector at the end of the migration path.

The inner walls of the silicate capillary carry negatively charged groups, so electroendosmosis is significant; this can be used for the purpose of separation, but it is usually suppressed by coating the inner wall with a polymer such as polyacrylamide gel or dextran. Separations based predominantly on size and shape differences are achieved in CZE in the presence of soluble polymers to produce a molecular sieve effect. A variety of uncharged hydrophilic polymers in a wide range of molecular weights are available for that purpose (2-4). Although providing high resolving power, gels are less applicable to CZE because the gelation process may introduce air bubbles and inhomogeneities within the capillary; also, a gel-filled capillary can only be used once or a few times, while polymer solutions can be replaced easily. One drawback of CZE is that the analyte bands are enclosed within the tube and therefore are unavailable for detection by immunological, hybridization, and staining techniques. However, the eluate of CZE can be subjected to mass spectrometry to provide molecular weights of the species detected, in addition to their mobilities (5).

References

1.F. Foret and P. Bocek (1989) Adv. Electrophoresis 3, 273–347. 

2. K. Ganzler, K. S. Greve, A. S. Cohen, B. L. Karger, A. Guttman, and N. C. Cooke (1992) Anal. Chem. 64, 2665–2671. 

3. M. C. Ruiz-Martinez, J. Berka, A. Belenkii, F. Foret, A. W. Miller, and B. L. Karger (1993(Anal. Chem. 65, 2851–2858 

4. D. Tietz, A. Aldroubi, H. Pulyaeva, T. Guszczynski, M. M. Garner, and A. Chrambach (1992) Electrophoresis 13, 614–615. 

5. D. Figeys, I. van Oostveen, A. Ducret, and R. Aebersold (1996) Anal. Chem. 68, 1822–1828.