A new type of migrating zone boundary in electrophoresis: 1. General description of boundary behavior based on electromigration dispersion velocity profiles

Abstract

Till now two principal types of electrophoretic boundaries have been recognized: a steady-state one showing self-sharpening properties and an unsteady-state one showing electromigration dispersion (EMD). In this contribution, the existence of a third (hybrid) type of electrophoretic boundary is revealed, that shows simultaneously: (i) steady-state character with self-sharpening properties in a certain part of the boundary, demarcated by a certain range of its composition; (ii) unsteady-state character with EMD in the resting part. A new theoretical approach to the study of the structure and properties of electrophoretic boundaries is presented, based on EMD velocity profiles representing the dependence of the EMD velocity on the composition in any point of the transition region across the boundary. According to this approach, the linearity or nonlinearity of the EMD velocity profile is recommended as the criterion for distinguishing the actual type of the boundary in question. It is shown that the new type of electrophoretic boundary is not an exotic case but may be observed even in simple systems as, e.g., formed by adjacent zones containing mixtures of current species such as picrate and acetate. Computer simulations are presented which confirm the theoretical conclusions and illustrate the three types of electrophoretic boundaries.

A new electrophoretic focusing principle: Focusing of nonamphoteric weak ionogenic analytes using inverse electromigration dispersion profiles

“…pH is usually increasing toward the anode in anionic profiles. Recently, we have described various cases of nonlinearity in EMD profiles [14][15][16][17][18] and shown that in special cases EMD profiles may have the course of pH along the profile inverted [18]. The aim of this article is to show that this special type of EMD profile of inverse character is really capable of focusing nonamphoteric analytes.…”

“…EMD profiles have some special properties that are described in detail elsewhere [13,14]. Here, we briefly describe the characteristics of an anionic EMD profile potentially suitable for focusing.…”

Dynamic computer simulations of electrophoresis: A versatile research and teaching tool

“…progressively broadening) electrophoretic boundaries that are produced between strong and weak electrolytes upon current flow [2,3,46,64,126,127,139] (for examples see Figs. 4-6 and 8-12), was used to discover and understand new types of migrating boundaries [140][141][142][143], provided insight into the regulation principles associated with current flow [2,3,46,123,124,127,144] , which is a strong acid with a mobility equal to that of the buffer additive and which was sampled together with the neutral analytes. S and I refer to the anionically migrating system peak and the location of the initial sample compartment, respectively.…”

Microfluidic free-flow electrophoresis for proteomics-on-a-chip

“…The goal of FFZE is to achieve high resolution, which is reached by analytes migrating and electromigration dispersion (σ EMD ) [17,32]. Not all sources of band broadening are discussed here and the reader is referred to the literature for more details.…”

“…Zones of different electrical conductivity in sample and carrier electrolyte will lead to electromigration dispersion [17,32]. This type of distortion results from different migration velocities of the analytes in zones having different electrical field strengths.…”