Question

Briefly discuss the different types of capillary electrophoresis, and some of the pro’s and con’s, as well as the key applications, of each type.

Answer 1

The different types of capillary electrophoresis are

1) capillary zone electrophoresis (CZE): The most popular and common capillary electrophoresis. It is based on is based on the differences in electrophoretic mobility, This depends on ratio of the particle’s charge to mass. The particles with larger charge to mass ration are separted first followed by the lower ratio. The capillary use silica gel. Which helps in holding the positively charged ion by silicate anion.

It is a quick and easy tehcnique

However it is good only for protein separaion where pI difference is low and large volume of samples is required for analysis/

Applicaiton: Serum & urine protein electrophoresis

Electrophoresis of isoenzymes and hemoglobin

2) capillary gel electrophoresis (CGE):

Based on the size of solute during migration of particles through gel.

It helps in reducing solute diffusion by preventing solute absroption by the walls. Also control the heat transfer. small amount of sample is required.

Highly dependant on the pH of buffer.

Application:analysis of protein-based pharmaceuticals and quality controls.

3) micellar electrokinetic capillary chromatography (MEKC): It is based on the distribution of solute partilces between micelles and the solvent.we use surfactants to form micelles. Micelle is an aggregate of surfactant molecules which have a polar head (towards solvent) and non polar tail (in the centre). The hydrophobic moleules will get attracted towards micelle while the hydrophillic molecules will move towards solvent.

Diadvantages are:The sensitivity cannot be related to practical samples and there is chance of contamination of ions souce by Nonvolatile surfactants and chiral selectors.

Advantages: it is environment friendly technique as low amount of solvent is used. It is an effecient technique. it can separate chiral compounds.

Application: determination of antibiotics like ampicillin, Sulfamethoxazole,Amoxicillin etc

4)capillary electrochromatography (CEC)L it is based on combined principle of capillary electrophoresis and High performance liquid chromatography.

Advantages: improved version of HPLC and does not restrict the application for column size and particle size.

But it is a very recent technique so need to be improved based on reproducibility of results

Smaller samples are required

It is used in hosptials for analyazing smaller amount of compounds in small amount of patient samples

5) capillary isoelectric focusing (CIEF)L separation based on the isoelectric points of proteins.

It is not useful for chiral compounds

Based on pH gradient

Protein with very little difference in pI (0.001) can be separated.

6) capillary isotachophoresis (CITP): Here charged molecules are separated based on the their mobility.

It is a simple and fast technique which requires small amount of sample.

It is used in biomedical fields for analyzing proteins. In forensic analysis.

There is reproducibility problem