On the one hand, it is crucial to have formulas that can be written in closed form, without relying on numerical integration for every transformation. Without such closed formulas it would be impossible to derive the correction factors for the peak areas that will be presented later in the article. On the other, this is already the case in virtually every CE setup. Contrast with LC, where gradients of retentivity have an intrinsic positive effect on separation. In CE, a high electric field will normally just induce a better separation, as it linearly affects the migration speeds. The "ramp phase" of the electric field is often required for mostly instrumental reasons. This allows us to parametrize an arbitrary electric field profile E(t) by