Isotachophoresis

It is a form of electrophoresis; charged analytes are separated based on ionic mobility, a quantity which tells how fast an ion migrates through an electric field.

If present in sufficient amounts, focusing analyte ions can displace all electrolyte co-ions, reaching a plateau concentration.

[1] A completed ITP separation is characterized by a dynamic equilibrium in which all coionic zones migrate with equal velocities.

From this phenomenon ITP has obtained its name: iso = equal, tachos = speed, phoresis = migration.

When all of the TE ions are dissolved, the focusing process ceases and the analytes are separated according to the principles of zone electrophoresis.

Stadia during an ITP separation of a mix of two analytes.
White: leading electrolyte; gray: terminating electrolyte; hatched: the analytes
The self-sharpening effect in ITP: due to a difference in electrical field, an ion will move faster when it comes in the previous zone, and slower when it comes in the next zone. Therefore, it will return to its own zone. Below the corresponding electrical field for each zone