Limiting migration velocity

For each ion the limiting migration velocity results from the equilibrium between the electric force F, which is exerted in the electric field E acting on the particle of charge q, and the forces resulting from the solution viscosity 17. Neutral... 

Electroimmunoassay (rocket electrophoresis) and radial immunodiffusion (A5) lack sensitivity at low Lp(a) concentrations, and the response is influenced by the size of the apo(a) isoforms (A5, K28). Differences in migration velocity in the agarose gel lead to an underestimation of the samples with large apo(a) isoforms and to an overestimation of samples with small apo(a) isoforms. Moreover, the detection limit lies around 0.07-0.08 g/liter Lp(a), so that this method is better suited for screening and detection of individuals with elevated Lp(a) levels than for the exact measurement of the plasma Lp(a) concentration. 

Size exclusion chromatography (SEC) is based on a particular type of separation. The migration velocity of a given component depends on its size thus, indirectly, on its molecular mass. The instrumentation used is similar to that used in HPLC. Although its column efficiency is far from ideal, SEC has become an irreplaceable tool in the area of the separation of natural or synthetic macromolecules. However, its application in analysis is more limited the separation of compounds according to their size is not the most efficient process for small or intermediate molecules. It is, however, a very useful process in industry for the separation of compounds with very different masses. 

Recent results by Chen et al. (1999) show, however, the transport velocity of H+ in natural soils during EO is considerably more retarded compared to the migration velocity in pure low CEC clays such as kaolinite. In EO experiments containing only pure kaolinite, very rapid electromigration of H is observed relative to natural soils because kaolinite is essentially a stoichiometric clay mineral and has limited capacity in absorbing cations. The transport ofH+ is therefore rapid. 

Method validation includes determination of performance characteristics such as selectivity (which determines accuracy), linearity, precision, and sensitivity (limit of detection). This work evaluated linearity, precision, and sensitivity for specific CZE separation conditions selectivity was reported previously (15). Factors that contribute to assay imprecision by affecting peak shape (such as the pH of the mobile phase) or migration velocity (pH effects on the electrophoretic velocity) were evaluated also. 

As the limiting charge on the particle is proportional to the radius squared, the migration velocity of the particle will increase with particle size. As the electric field is proportional to the applied voltage, the migration velocity is proportional to the voltage squared. 

Under normal operating conditions, the limiting charge is approached after a time small compared with the time of gas treatment in a precipitator. When we combine (2,38) with (2.35), it is found that the migration velocity for field charging increases linearly with particle size when / is given by Stokes law. 

Based upon such data, direct analysis of some fractions is possible when the components can be identified by their mobility alone. However, such an application is very limited in practice, as many subfractions have almost equal mobilities. In order to measure relative mobilities, it is practical to use pure serum albumin as reference. If the mobility of the latter is aib and the mobility of the unknown protein Ux, the quotient x/Waib is independent of the carrier medium if the migration velocity does not change during the run. In Table 3, relative mobilities... 

Migration is due to forces acting upon particles. When a force acts upon a particle, it will accelerate and friction forces will limit the velocity to a value proportional to the force. The average velocity of a species in the solution acted upon by a force of 1 Newton/mole is called the me hani cal m bj l ty u (mol.m/Ns). 

Haj-Hariri et al. [38] calculated the change to the migration velocity caused by deformation.Balasubramaniam and Subramanian [39] found asymptotic solutions for Ma 1 in the limits Re 1 and Re l. For Re 1, they showed that... 

In TLC, the solvent velocity is the parameter which, in principle, cannot be influenced by the chromatographer. The enhanced efficiency of FFPC techniques by comparing TLC where the mobile phase migrate only by capillary action is the constant linear mobile phase velocity. FPTC techniques guarantee the optimal H/u values. In OPLC the upper limit of velocity depends on the applied external pressure, besides the viscosity. In RPC, the higher the rotational speed, the faster the migration of the mobile phase. 

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