In this form, it interpolates between zero mobility, for analytes arriving with the EOF (t M t EOF ), and mobility µ A , for analytes arriving with A. As in the general two-marker formula, the interpolation is not linear. We can see an example of the shape of µ as a function of t in Figure . The two-marker formula in has an additional advantage, already seen in . In the search to eliminate the instrumental parameter v p that appeared as a consequence of the field ramp, we have also gotten rid of the field and capillary length, E and L. Because of this, even in absence of a field ramp, the two-marker formula can actually be an improvement in terms of precision with respect to the known one-marker formula (due to inexact values of the effective capillary length, parasitic resistances affecting the actual value of the field applied to the capillary, etc.).