Monday, 22 October 2012

Electrophoresis - An Electro Kinetic Phenomenon


Electrophoresis is one of the Electro Kinetic Phenomenon (a family of several different effects that occur in heterogeneous fluids i.e the fluids containing particles which can be solid, liquid or gaseous). It was first observed by Ferdinand Frederic Reuss in 1807.

1) The Colloidal particles carry an Electric charge on it either
Positive(+) or Negative(-).

2) Due to this charge present on colloidal particles, they move
towards one of the electrodes when an electric Potential is applied to the Sol(Colloidal solutions).

3) This migration of colloidal particles under the influence of an
electric field is called as "Electrophoresis".

4) In the other words, on the basis of Electrophoresis phenomenon it
is possible to detect the charge present on the colloidal particles.

5) This can be studied with the help of an simple experimental set up.

6) Consider that in a U-shaped glass tube Colloidal solution is taken.
A small amount of electrolyte having lower density than sol is also introduced in the U-tube.

7) Due to it's lower density the electrolyte is displaced upward and a
sharp boundary is formed between the sol and the electrolyte.

8) Now a Positive electrode is immersed at one end of the U-tube
whereas the Negative electrode is immersed at the another end and the electricity is passed.

9) The colloidal particles will move towards one of the electrodes.

10) If they move towards Positive(+) electrode then they are
Negatively (-) charged whereas if they move towards Negative(-) electrode then they are Positively(+) charged.

11) Electrophoresis shown by positively charged particles i.e cations
is called as Cataphoresis , while Electrophoresis shown by negatively charged particles i.e anions is called as Anaphoresis .

12) Amino acids,Nucleotides,Polypeptides,Proteins and many other
compounds in their colloidal states can be separated by Electrophoresis.