Electrophoresis boundary

Zone electrophoresis is defined as the differential migration of a molecule having a net charge through a medium under the influence of an electric field (1). This technique was first used in the 1930s, when it was discovered that moving boundary electrophoresis yielded incomplete separations of analytes (2). The separations were incomplete due to Joule heating within the system, which caused convection which was detrimental to the separation. 

In order to illustrate the effects of media structure on diffusive transport, several simple cases will be given here. These cases are also of interest for comparison to the more complex theories developed more recently and will help in illustrating the effects of media on electrophoresis. Consider the media shown in Figure 18, where a two-phase system contains uniform pores imbedded in a matrix of nonporous material. Solution of the one-dimensional point species continuity equation for transport in the pore, i.e., a phase, for the case where the external boundaries are at fixed concentration, Ci and Cn, gives an expression for total average flux... 

Douglas et al. [98] have measured protein (serum albumin, ovalbumin, and hemoglobin) mobilities over a range of pH values using a free-flow electrophoresis apparatus and a particle electrophoresis apparatus. They found good agreement between the two measurements however, they also found some differences between their measurements and those reported in the older literature. They attributed the differences to the use of moving-boundary electrophoresis methods in the early experimental work and to differences in... 

The form of the effective mobility tensor remains unchanged as in Eq. (125), which imphes that the fluid flow does not affect the mobility terms. This is reasonable for an uncharged medium, where there is no interaction between the electric field and the convective flow field. However, the hydrodynamic term, Eq. (128), is affected by the electric field, since electroconvective flux at the boundary between the two phases causes solute to transport from one phase to the other, which can change the mean effective velocity through the system. One can also note that even if no electric field is applied, the mean velocity is affected by the diffusive transport into the stationary phase. Paine et al. [285] developed expressions to show that reversible adsorption and heterogeneous reaction affected the effective dispersion terms for flow in a capillary tube the present problem shows how partitioning, driven both by electrophoresis and diffusion, into the second phase will affect the overall dispersion and mean velocity terms. 

Boyack, JR Giddings, JC, Zone and Boundary Diffusion in Electrophoresis, The Journal of Biological Chemistry 235, 1970, 1960. 

Chrambach, A, Unified View of Moving Boundary Electrophoresis Practical Implications, Journal of Chromatography 320, 1, 1985. 

Hoyt, JJ Wolfer, WG, Boundary Element Modeling of Electrokinetically Driven Fluid Flow in Two-Dimensional Microchaimels, Electrophoresis 19, 2432, 1998. 

Shimao, K, Mathematical Simulation of Isotachophoresis Boundary Between Protein and Weak Acid, Electrophoresis 7, 297, 1986. 

Electrophoresis. Electrophoresis, the movement of charged particles in response to an electric potential, has become very important in biochemistry and colloid chemistry. In the present study an apparatus similar to that described by Burton( M2-M5) was used. A U-tube with an inlet at the bottom and removable electrodes at the two upper ends was half filled with acetone. The a Au-acetone colloidal solution was carefully introduced from the bottom so that a sharp boundary was maintained between the clear acetone and the dark purple colloid solution. Next, platinum electrodes were placed in the top ends of the U-tube, and a DC potential applied. The movement of the boundary toward the positive pole was measured with time. Several Au-acetone colloids were studied, and electrophoretic velocities determined as 0.76-1.40 cm/h averaging 1.08 cm/h. 

Influence of the Surface Concentration of BSA. Compared to the corrected moving boundary electrophoretic mobility of BSA in solution, the mobility of BSA adsorbed onto glass is considerably faster at all ionic strengths at 1.96 pg/cm2 and somewhat faster at lower ionic strengths 1.38 pg/cm2. However, at lower adsorption densities (1.05 and 0.64 pg/cm2), the adsorbed BSA moves more slowly in the applied electric field than BSA in moving boundary electrophoresis under otherwise identical conditions, and at the lowest surface adsorption (0.64 pg/cm2) the mobility of the adsorbed BSA are even somewhat slower than in cellulose acetate gel at all conditions of ionic strength investigated. 

TABLE 4 Comparison of the adsorbed BSA electrophoresis results of Tables 1 and 2, with cellulose acetate electrophoresis (Table 3) and moving boundary electrophoresis [6], extrapolated to 30°C (as in Tables 1 and 2) and to the appropriate ionic strengths (Tables 1-3)... 

The origins, principles, methods, and modes of capillary electrophoresis (CE) are discussed. Massive application of electrophoresis methods started after Tiselius s moving boundary method that was optimized by the use of paper or a gel as a semiconducting medium. The applications of paper and gel electrophoresis were situated mostly in the biochemical environment for the analysis of proteins, amino... 

With the study of the migration of hydrogenium ions (H ) in a phenolphthalein gel by Lodge in 1886 and the description of the migration of ions in saline solutions by Kohlraush in 1897, a basis was set for the development of a new separation technique that we know today as electrophoresis. Indeed, several authors applied the concepts introduced by Lodge and Kohlraush in their methods and when Arne Tiselius reported the separation of different serum proteins in 1937, the approach called electrophoresis was recognized as a potential analytical technique. Tiselius received the Nobel Prize in Chemistry for the introduction of the method called moving boundary electrophoresis. ... 

Also known as copper blue. maunt on blu ) moving-boundary electrophoresis analychem A U-tube variation of electrophoresis analysis that uses buffered solution so that all ions of a given species move at the same rate to maintain a sharp, moving front (boundary). miivii) baun-dre i lek-tro-fo re-sos ... 

The potential differences, /, at different phase boundaries, as mentioned before, have been found to have many industrial applications. The application of electrophoresis to the separation and purification of proteins has also been discussed. Both electrophoresis and electroosmosis have attained a certain amount of industrial application. 

A Tiselius. Moving boundary method of studying the electrophoresis of proteins. Nova Acta Reg Soc Uppsal Ser IV 7 1-107, 1930. 

The schlieren system of optics is an analytical method that is particularly well suited to following the location of a chemical boundary with time. It is routinely employed in ultracentrifuges and also in electrophoresis experiments, as we see in Chapter 12. Schlieren optics produces an effect that depends on the way the refractive index varies with position, that is, the refractive index gradient rather than on the refractive index itself. Therefore, the schlieren effect is the same at all locations along the axis of sedimentation, except at any place where the refractive index is changing. In such a region, it will produce an optical effect that is proportional to the refractive index gradient. The boundary between two layers is thus per-... 

These equations (and others that follow) are based on the solutions of equations of motion for the particles, as well as the electrolyte, that we use in Chapter 12 in the context of electrophoresis. It turns out that the analysis of Krasny-Ergen fails to satisfy one of the boundary conditions and does not take into account energy dissipations caused by the electric currents arising from the motion of the electrolyte. It is more appropriate for kRs -> oo. 

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