A new type of migrating zone boundary in electrophoresis: 2. Transient sample zone shapes

Abstract

A new type of migrating zone boundary in electrophoresis is presented theoretically and evidenced experimentally. This type of the boundary (called hybrid boundary) shows simultaneously a steady-state part with self-sharpening properties and an unsteady-state part with time-dependent electromigration dispersion. It is shown that a sample zone may possess a hybrid boundary both as its front and rear one simultaneously. In such a case, the evolution of a sample zone injected originally as a rectangular pulse exhibits very complex transient shapes before it reaches the well-known fronting or tailing triangular shape. Depending on the stage at which detection of such a sample zone occurs, variable and peculiar-shape peaks may appear in the electropherogram. Based on theoretical predictions, experimental examples of the above-mentioned phenomena are presented in this contribution for direct and indirect UV absorbance detection of sample zones. Excellent agreement of theoretical predictions with the experiments has been found. The knowledge of hybrid boundaries is of key significance for correct interpretation of records of CE analyses in practice.

Regular properties of simple electrophoretic BGEs with multiprotic weak acids: Discovery of complex hybrid system boundaries

“…It depends on the order of both zones forming the profile and on the direction of passage of electric current whether a D-type or S-type profile is formed. Recently, we have shown [1][2][3] examples of systems where the moving boundary is of a hybrid type and consists of a self-sharpening part and a diffuse EMD part. Hybrid boundaries are formed when the velocity curve is not a monotone function in the sense that several different local zone compositions possess the same velocity.…”

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

“…As already noticed, the common natural course of pH in EMD profiles is unfortunately opposite. Only in the last years, systems were discovered that show nonlinear behavior and where a part of the EMD profile shows an inverse course of pH [14][15][16][17][18]. To demonstrate the existence and properties of the new focusing principle in simple systems, we have selected two examples in which the EMD profiles formed are of system nature and the entire electrolyte setup is made of only one multivalent weak acid and one cationic counter-substance [18].…”

“…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.…”

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.…”

“…In recent work, Gebauer et al used SIMUL 4.0 [141,142] and SIMUL5 [143] to evaluate and describe new types of boundaries that feature both steady-state (sharp) and nonsteady-state (broadening) properties. Simulation results of such a hybrid system comprising picrate and acetate are shown in Fig.…”