Capillary Electrophoresis

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CAPILLARY ELECTROPHORESIS

Capillary Electrophoresis



Table of Contents

Introduction1

Main theory underpinning the technique2

Main features of the instrument2

Sample preparation requirements4

Two analytes4

Chemical/physical properties of each analyte4

Relation of analyte with analytical technique6

Conclusion6

References8

Capillary Electrophoresis

Introduction

Capillary zone electrophoresis or capillary electrophoresis is a chemical technique used in the separation of ionic species from their frictional forces and hydrodynamic radius. The analytes in this technique are charged electrically using an electric field and are then placed in a conducive liquid medium. The technique which is now used very commonly was first discovered back in the year 1960s was used to separate various sizes of species. Through the technique the inferior of these species gets electrically charged. The capillary tube that is used in the experiment contains an electrolyte that facilitates the overall separation. Other than this, there are many other utilities of Capillary Electrophoresis such as discovery of drugs and others.

The method is very powerful and is older than molecular biology itself. The technique is based on the principle that when molecules are charged they tend to travel towards the opposite pole in an electrical field. This travelling of the molecules is based on the physical properties of the molecules. Capillary electrophoresis is a development of the traditional electrophoresis which had two major problems. Firstly, upon completion of the process, it was very difficult to detect the molecules. Secondly, the technique could involve only two voltages. These were used to prevent the heat from damaging the samples. Both these problems have been solved with the capillary electrophoresis. The technique is now used very widely in biomolecular and pharmaceutical researches. This is so because the separation power of this technique is much higher than its alternatives. The application is broad and ranges from experiments that pertain to protein to peptide and even genetic analysis. The most recent use of capillary electrophoresis has been made by drug testing agencies and laboratories who are using it for High Throughput Screening also termed shortly as HTS. This is one of the most successful experiments to date that relates to capillary electrophoresis in which 6 million compounds were deposited or rather separated on over 150 targets. This made possible for the scientists to make multiple leads.

Main theory underpinning the technique

The theory underlying the technique is the electrolyte theory. The whole experiment is based on the electrolytic process whereby a certain level of voltage is applied to an ion containing field which separates the ions based on the charge they contain. The cations and anions get separated and deposit on their relevant terminal also called electrodes (Finn & Glicksman, 2000, p. 25). In addition, the attraction of an ion towards an electrode is based on the fact that opposite charges attract each other whereas similar charges repel each other. In other words, the positively charged ion cation is attracted towards the positive electrode whereas anion or the negatively charged ion is attracted towards the positive electrode.

Other relevant concepts to capillary electrophoresis are Rate of Migration theory, the concept of Ionic Mobility, and Electro-Osmotic Flow ...