Electroosmotic flow variance

The standard deviation of the Gaussian zones expresses the extent of dispersion and corresponds to the width of the peak at 0.607 of the maximum height [24,25]. The total system variance (ofot) is affected by several parameters that lead to dispersion (Eq. 17.22). According to Lauer and McManigill [26] these include injection variance (of), longitudinal (axial) diffusion variance (of), radial thermal (temperature gradient) variance (of,), electroosmotic flow variance (of,), electrical field perturbation (electrodispersion) variance (of) and wall-adsorption variance (of ). Several authors [9,24,27-30] have described and investigated these individual variances further and have even identified additional sources of variance, like detection variance (erf,), and others... 

Electroosmotic flow variance. As the flow profile of the EOF is flat, almost like a piston, its contribution to dispersion of the migrating zones is small. The EOF positively contributes to the axial diffusion variance, as can be derived from Eq. 17.26, when it moves in the similar direction as the analytes. However, when the wall of the capillary is not uniformly charged, local turbulence can occur and cause irreproducible dispersion [27]. 

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