Electrophoresis zone broadening

The width of a peak, or, in other words, the length of a solute zone, is affected primarily by diffusion phenomena leading to a broadening of the solute zone. In addition, in capillary zone electrophoresis, zone broadening can be caused by thermal effects, electrodispersion, or adsorptive effects. All these effects can be expressed as coefficients of variance cr2, adding to a total coefficient of variance of the system ofotal ... 

Moore, A.W., Jorgenson, J.W. (1993). Study of zone broadening in optically gated high-speed capillary electrophoresis. Anal. Chem. 65, 3550-3560. 

Hjerten, S. (1990). Zone broadening in electrophoresis with special reference to high-performance... 

What is the principal source of zone broadening in ideal capillary electrophoresis ... 

The heat generated during electrophoresis is proportional to the square of the applied current and to the electrical resistance of the medium even when a supporting medium is used, heat production will lead to zone broadening... 

Table 12.1 shows the variety of capillary electrophoresis detection methods that have been tested to date, as well as their reported detection limits. While detection limits for instrumental methods are usually reported in concentration units, those reported for CE methods are generally given in moles because of zone broadening (the peak concentration at the detector is always less than the concentration injected) and the variety of injection volumes that are possible between instruments with different sized capillaries and different injection and operating potentials. 

In the ultimate limiting case, if all other mechanisms of zone spreading can be rendered insignificant, zone broadening in zone electrophoresis will be dominated by a seemingly unpreventable mechanism, longitudinal diffusion. As diffusion in liquids is rather slow, this may result in rather narrow zones. 

Capillary zone electrophoresis (CZE) appears to be a most powerful technique, perhaps equaling the resolving power of IPG. If one assumes that longitudinal diffusion is the only significant source of zone broadening, then the number of theoretical plates N in CZE is given by [149] ... 

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