Capillary electrophoresis is one type of technique in which solute molecules are separated, by applying high voltage (1000v).

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Capillary electrophoresis

Capillary electrophoresis is one type of technique in which the solute molecules are separated by electrophoretic mobility and electro-osmotic force.

In other words;

Capillary electrophoresis is one type of sepration technique in which solute molecules are seprated using narrow bore capillary.

Instrument required for sepration of sample

1. Two buffer reservoirs filled with buffer solution.

2. Polymicro fused silica capillary, it is extends between two buffer reservoirs.

3. Cathode and anode are placed in the buffer solution in separate reservoir.

4. Electrode are contented to high voltage (power supply).

5. High Voltage (1000v) are required for proper sepration/Operation.

All arrangements for this operation technique is shown in fig.

there are two end of capillary required for operation

1. First end – sample can be introduced in first end of capillary.

2. Second end – detector are connected the other end of capillary.

Function of detector – the function of detector is detect the presence of a particular object or any type of substance.

Operation Process;

When capillary end are injected (dip) in buffer solution, the buffer solution will start raised in capillary with the help of capillary action.

When buffer solution is raised in capillary due to capillary action and that point we will apply voltage between the electrode. the buffer solution start flowing in the capillary.

If current supply for this operation, current will strat flow and buffer solution are following in the capillary. at that position electro-osmotic force are generated.

There are two main terms are apply in this operation, such as

1. Electro-osmotic Force

2. Electrophoretic Mobility


When the voltage are apply accross the electrode buffer start flow through the capillary. at that time electro-osmotic forces are generated.

When the voltage is applied across the capillary cation in diffuse layer will get attracted towards cathode dragging easily the bulk solution with them. this phenomenon is called electro-osmotic force.

in this capillary, anode has + charge and cathode has negative charge when high voltage are apply at that time the cation from bulk solution will get attacked towards cathode. it mean that (example) “the directions of flow of solution in capillary dragging the bulk solution with it“.

Electrophoretic Mobility;

electrophoretic Mobility indicate the rate of migration of solute molecules. it is represent in cm/sec.

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Construction of Capillary

It is made up fused silica. It has silanol groups are present on the inner surface of capillary. the inner dimeter of capillary is 10 – 100 micro meter. and length is 40 – 100 cm. (inner capillary)

the polyimide coating is in inner of capillary, because it is protect capillary. the inner dimeter of capillary even thiner of our hair. the dimeter of capillary is very thiner, such as 10 – 100 micro meter. it is just equivalent to human hair.

the inner surface of capillary is negative charged. and there are 3 types of layer is in capillary. such as,

these both layer is shown in cross section of capillary.

  1. Fixed layer
  2. Diffuse layer
  3. Bulk solution

  1. Fixed layer

You know that, the inner surface of capillary is negative charged. it will attract cation from buffer solution these cation are tightly on the inner surface of capillary. Forming of fixed layer. these layer is fixed. as we know capillary is circular cross section one more diffuse layer and fixed layer.

2. Diffuse layer

it will attract more number of cation from buffer solution forming diffuse layer, in diffuse layer no of cation is more then no of ainion.

3. Bulk solution

In case of bulk solution, Bulk solution in capillary where the number of cation and number of ainion is equal. these are the basic concept of this three layers for capillary.

As we know,

Total velocity of solute – electro – osmotic flow + electrophoretic Mobility”.

Frequently Asked Question

1. What is the difference between gel electrophoresis and Capillary electrophoresis?

gel electrophoresis – in this case, it is one type of separation technique in which it is separated slab gel matrix.

Capillary electrophoresis – it is also a one type of sepration technique in which it is separated solute molecules (liquid, gel, buffer) with the help of capillary tube.

2. What is main uses of electrophoresis?

Mainly, it is used for the sepration of solute molecules according to size and charge. it is performed with the help of polymicro called capillary. it is made by fused silica.

3. What is the basic principal or concept of electrophoresis?

the principle or basic concept of electrophoresis is to sepration of chemical charged particles (ions) with the help electric field. In this case, electrophoresis technique consist two electrodes. Such as,

  1. Anode
  2. Cathode

As you know, cathode has + charge and anode has – charge. it will work by applying high voltage with the help of electrolyte.

4. What is actually basic concept of capillary electrophoresis?

the basic concept of capillary electrophoresis is, it is one type of technique in which solute molecules or ions are separated with the help of applying high voltage around (1000v). the electrophoresis mobility is depend upon charge of molecules and viscosity of molecules.

If charge of molecules or size of molecules is higher then it improve the electrostatic force on it. larger particle has smaller eletrophoretic mobility.