Electrophoretic migration

Process Concept The application of a direct elec tric field of appropriate polarity when filtering should cause a net charged-particle migration away from the filter medium. This electrophoretic migration will prevent filter-cake formation and the subsequent reduction of filter performance. An additional benefit derived from the imposed electric field is an electroosmotic flux. The presence of this flux in the membrane and in any particulate accumulation may further enhance the filtration rate. 

Cross-flow-elec trofiltratiou (CF-EF) is the multifunctional separation process which combines the electrophoretic migration present in elec trofiltration with the particle diffusion and radial-migration forces present in cross-flow filtration (CFF) (microfiltration includes cross-flow filtration as one mode of operation in Membrane Separation Processes which appears later in this section) in order to reduce further the formation of filter cake. Cross-flow-electrofiltratiou can even eliminate the formation of filter cake entirely. This process should find application in the filtration of suspensions when there are charged particles as well as a relatively low conduc tivity in the continuous phase. Low conductivity in the continuous phase is necessary in order to minimize the amount of elec trical power necessaiy to sustain the elec tric field. Low-ionic-strength aqueous media and nonaqueous suspending media fulfill this requirement. 

Particulate systems require the addition of the term in order to account for the electrophoretic migration of the particle. The constant... 

An example of the results obtained in the form of a chromatoelectropherogram can be seen in Figure 9.6. The contour type data display showed the three variables that were studied, namely chromatographic elution time, electrophoretic migration time, and relative absorbance intensity. Peptides were cleanly resolved by using this two-dimensional method. Neither method alone could have separated the analytes under the same conditions. The most notable feature of this early system was that (presumably) all of the sample components from the first dimension were analyzed by the second dimension, which made this a truly comprehensive multidimensional technique. 

Giddings, JC Boyack, JR, Mechanism of Electrophoretic Migration in Paper, Analytical Chemistry 36, 1229, 1964. 

Radko, SP Chrambach, A, Electrophoretic Migration of Submicron Polystyrene Latex Spheres in Solutions of Linear Polyacrylamide, Macromolecules 32, 2617, 1999. 

Tejero-Diez, P., Rodriguez-Sanchez, P., Diez-Guerra, F.J. (1999). Microscale purification of proteins exhibiting anomalous electrophoretic migration application to the analysis of GAP-43 phosphorylation. Anal. Biochem. 274, 278-282. 

Because of the dominating role of EOF each analyte (cationic, anionic and neutral) has a tendency to move towards the cathode. The cation migration velocity is composed of the electrophoretic migration and the electroosmotic flow. Neutral analyses are not separated under common CE conditions, they move together with the electroosmotic flow. The migration velocity of anions is the difference between electroosmotic flow and electrophoretic migration, consequently their migration velocity is lower than that of neutral compounds and cationic ones. 

Although CE separations can be reasonable well described by the classical theoretical relationships for electrophoretic migration, slight deviations from the theory occur in the case of many classes of solutes. Thus, it has been reported that the CE separation of oligosaccharides follow the general rule [124], while the description of the separation of DNA in polymer solutions necessitated a new mathematical model. The drag forces were expressed by... 

The classical theory of electrophoretic migration has also been successfully applied to the description of the behaviour of human growth hormone peptides. According to the classical theory, the mobility (ju) of a peptide can be described by... 

Electrophoretic migration - A more than A reversibly unwinds supercoiled DNA A 48... 

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