In this section we will derive formulas to transform migration times to effective electrophoretic mobilities, taking into account non-constant fields and the possibility of using more than one marker in the spirit of . We will review the effect of these transformations on peak areas generalizing the results in . Finally, we will study their impact on peak shapes giving quantitative measures of peak displacement and deformation, and from them we will propose a priori rules for the optimization of precision of peak position.