size separation through analytical method...
It is an analytical technique which is used to separate particles based on their size.
Principle: This technique is mainly based on the migration of charged particles in presence of electrical field. When a molecule is placed in an electric field it will experience a force which is equal to
F=E/D * q
E is potential difference
q is net charge
d is distance between positive and negative electrodes(3)
It is of two types
* one dimensional gel electrophoresis: here only one plane of separation is possible like separation of DNA etc
* Two dimensional gel electrophoresis: separation is done on two planes like resolving proteins present in a cell (1)
Design of electrophoresis may be either
* Tube gel electrophoresis where glass tubes are filled with gels
* Slab gel electrophoresis where gel is spread over as slabs.
The gels used may be either agarose or polyacrylamide.
Procedure: Gel is taken and small wells are made in which the sample is taken. After this gel has to be immersed in a buffer which maintains the ph as well as supplies ions. When a substance like sodium dodecyl suphate is added and if the sample to be separated has proteins then the proteins become negatively charged as they bind to dodecyl sulphate anions .(2)
Detection: After the separation it can be detected by blotting on nitrocellulose or nylon fibers and treated with 0.25 N HCl.
Applications: It is widely used for separation of DNA molecules. (1)http://www.vivo.colostate.edu/hbooks/genetics/biotech/gels/principles.html (2)http://www.colorado.edu/outreach/BSI/pdfs/gel_electrophoresis.pdf (3)http://www.uvp.com/pdf/ab-1000-02.pdf