Electrophoretic mobility relationships

The presence of surface conductance behind the slip plane alters the relationships between the various electrokinetic phenomena [83, 84] further complications arise in solvent mixtures [85]. Surface conductance can have a profound effect on the streaming current and electrophoretic mobility of polymer latices [86, 87]. In order to obtain an accurate interpretation of the electrostatic properties of a suspension, one must perform more than one type of electrokinetic experiment. One novel approach is to measure electrophoretic mobility and dielectric spectroscopy in a single instrument [88]. 

The standard Rodbard-Ogston-Morris-Killander [326,327] model of electrophoresis which assumes that u alua = D nlDa is obtained only for special circumstances. See also Locke and Trinh [219] for further discussion of this relationship. With low electric fields the effective mobility equals the volume fraction. However, the dispersion coefficient reduces to the effective diffusion coefficient, as determined by Ryan et al. [337], which reduces to the volume fraction at low gel concentration but is not, in general, equal to the porosity for high gel concentrations. If no electrophoresis occurs, i.e., and Mp equal zero, the results reduce to the analysis of Nozad [264]. If the electrophoretic mobility is assumed to be much larger than the diffusion coefficients, the results reduce to that given by Locke and Carbonell [218]. 

Davies, R. and Prcece, A.W. (1983). The electrophoretic mobilities of minerals determined by laser Doppler velocimetry and their relationship with the biological effects of dusts towards macrophages. Clin. Phys. Physiol. Meas. 4, 129-140,... 

Electrophoresis occurs in electrolyte solutions, where a competition of two forces, the electric force Fe and the frictional force Ff, are in equilibrium. The relationship of the two forces determines the electrophoretic mobility of the compounds ... 

In order to influence a migration it is obvious that one can alter the charge of the compounds, the viscosity of the medium and the dynamic radius of the compounds. According to Eq. 17.5, the electrophoretic mobility is the proportionality factor in the linear relationship of the migration velocity and the electric field strength... 

The migration in CE is obviously influenced by both the effective and the electroosmotic mobility. Therefore, the proportionality factor in the relationship of the migration velocity and the electric field strength in such a case is called the apparent electrophoretic mobility (/iapp) and the migration velocity the apparent migration velocity (vapp). The /iapp is equal to the sum of /migration velocity is expressed as... 

The relationship between the electrophoretic mobility and the radius (r) and the net charge of the peptide is... 

Although the theory of polyelectrolyte dynamics reviewed here provides approximate crossover formulas for the experimentally measured diffusion coefficients, electrophoretic mobility, and viscosity, the validity of the formulas remains to be established. In spite of the success of one unifying conceptual framework to provide valid asymptotic results, in qualitative agreement with experimental facts, it is desirable to establish quantitative validity. This requires (a) gathering of experimental data on well-characterized polyelectrolyte solutions and (b) obtaining the relationships between the various transport coefficients. Such data are not currently available, and experiments of this type are out of fashion. In addition to these experimental challenges, there are many theoretical issues that need further elaboration. A few of these are the following ... 

Consequently, the SDS microemulsion system is the best model for indirect measurement of log Pow. However, this is valid only for neutral solutes. We reported that the relationship between MI and log Pow for ionic solutes is different from that for neutral solutes (49). This would be caused by the ionic interaction between ionic solutes and the ionic microemulsion as well as ionic surfactant monomer in the aqueous phase. Kibbey et al. used pH 10 buffer for neutral and weak basic compounds and pH 3 buffer for weak acidic compounds (53). Although their purpose was to avoid measuring electrophoretic mobility in the aqueous phase, this approach is also helpful for measuring log Pow indirectly. 

From the relationship existing between migration distance and electrophoretic mobility and between peak width and number of theoretical plates, the resolution can be expressed as... 

Figure 23 Fit of Effective Electrophoretic Mobilities, versus Q (Calculated According to the Relationship t,= q/MIm) for Peptides Separated Using a 50 mM Sodium Phosphate Buffer pH 3.0 324 ab...

In addition to differences in electrophoretic mobility between the various heritable types of red cell acid phosphatase, there are striking quantitative differences. Figure 13 (86) demonstrates that the mean level of enzymic activity of type B acid phosphatase is considerably greater than the mean level of type A. Type BA lies almost exactly between the two curves. The genetic relationships of the human isoenzymes have been reviewed by Giblett (79). 

Model particle mobility has been determinated with the Tiselius method (Tiselius, 1937, 1938). This method also allows the integration of the mobility of a large number of particles even if the refractive index is very close to that of the electrolyte medium, allowing to minimize the experimental errors inherent to the classical microelectrophoretic techniques. The electrophoretic mobilities will not be transformed into surface charges because the theoretical relationship between these parameters is highly dependant on the particle radius of curvature and the electrolyte concentration in the vicinity of the particle (Hunter and Wright, 1971). For both methods, the analytical error falls below 5 %, however, it increases up to 10 % for natural composite samples and/or low mobilities. 

Figure 8.11 Electrophoretic mobility and zeta potentials of sheep erythrocyte. (Left) Relationship between true electrophoretic mobility in sheep erythrocyte and pH using NCE chips coated with BSA, gelatin, and MPC polymer. (Right) Relationship between sheep erythrocyte zeta potentials and pH using NCE chips coated with BSA, gelatin, and MPC polymer [39].

Jalali-Heravi, M., Shen, Y., Hassanisadi, M., and Khaledi, M. G. (2005). Prediction of electrophoretic mobilities of peptides in capillary zone electrophoresis by quantitative structure-mobility relationships using the Offord model and artificial neural networks. Electrophoresis 26,1874—1885. 

The Relationship Between the Electrophoretic Mobility and the Adsorption of Ions on Polystyrene Latex... 

Fig. 7.1. Schematic that summarizes the relationship between the various micro-separation techniques. Line 1 lists the various micro-separation techniques. Below each method in line 2 is the type of flow or combination of flow (=>) that exists for each technique while in line 3 is the relative contribution of solute/bonded phase interactions and electrophoretic mobility to the separation mechanism.

A persistent question regarding carbon capacitance is related to the relative contributions of Faradaic ( pseudocapacitance ) and non-Faradaic (i.e., double-layer) processes [85,87,95,187], A practical issue that may help resolve the uncertainties regarding DL- and pseudo-capacitance is the relationship between the PZC (or the point of zero potential) [150] and the point of zero charge (or isoelectric point) of carbons [4], The former corresponds to the electrode potential at which the surface charge density is zero. The latter is the pH value for which the zeta potential (or electrophoretic mobility) and the net surface charge is zero. At a more fundamental level (see Figure 5.6), the discussion here focuses on the coupling of an externally imposed double layer (an electrically polarized interface) and a double layer formed spontaneously by preferential adsorp-tion/desorption of ions (an electrically relaxed interface). This issue has been discussed extensively (and authoritatively ) by Lyklema and coworkers [188-191] for amphifunctionally electrified... 

Figure 1 Schematic representation of the relationship between the logarithmic normalized electrophoretic mobility (j l/j l0) and the molecular size (L). Rg, radius of gyration. (Reproduced with permission from Ref. 161.)...

Table 1. Relationship between X and the physical solute properties using different FFF techniques [27,109] with R=gas constant, p=solvent density, ps=solute density, co2r=centrifugal acceleration, V0=volume of the fractionation channel, Vc=cross-flow rate, E=electrical field strength, dT/dx=temperature gradient, M=molecular mass, dH=hydrodynamic diameter, DT=thermal diffusion coefficient, pe=electrophoretic mobility, %M=molar magnetic susceptibility, Hm=intensity of magnetic field, AHm=gradient of the intensity of the magnetic field, Ap = total increment of the chemical potential across the channel...

For particles, the electrophoretic mobility pe is related to their surface charge density, which is best expressed in terms of the -potential. For moderately charged particles ( -potential < 25 mV), this relationship is given by Eq. (75), where the function f(KDdH) varies smoothly between 1.0 and 1.5 as kd varies between very small and very large values [264] ... 

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