Electrophoretic Mobility and Velocity

Effective mobility p of an ionic substance in a solution can be expressed as a function of many factors as follows:

where m0 is the absolute mobility of a solvated ion, Ka the acid dissociation constant, pH the pH of the solution, T the temperature, y the viscosity of the solvent used, s the dielectric constant of the solvent, I the ionic strength, Ks the stability constants of the complexes or ion pairs formed, and Ccomp the concentration of the complex-forming agent or the ion pair-forming agent.

Eqn [1] shows that the effective mobility is a complex function of the properties of the sample ion, the solvent used and the coexisting ions. A basic idea of the electrophoretic separation is to vary the mobilities of the ions being separated by varying some of the factors in the above function.

The migration velocity of the ion (v)i can be expressed as:

where E is the potential gradient of the electrical field. Consequently the difference of the electrophoretic velocities among separands is the driving force of the electrophoretic separation.

The name of 'isotachophoresis' comes from the Greek for equal (iso, iso) velocity (tacho, tachoz) sample dragging (phoresis, foreesqai). Although this name characterizes its principle as described later, if the sample velocities were the same throughout the migration process, there would be no separation.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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