Wednesday, March 29, 2017

Thin Layer Chromatography Vs Column Chromatography

Thin-Layer Chromatography- An Introduction
There are many different types of chromatography in use to separate components of various mixtures. One of the most commonly used is Thin Layer Chromatography or TLC, as it is popularly known as. Thin Layer Chromatography is mainly employed to separate non-volatile mixtures. This form of chromatography works by coating a glass sheet, plastic or aluminium foil with adsorbent material like Silica Gel, Aluminium Oxide and Cellulose and then passing the mixture through it. This mixture is generally known as the mobile phase. Depending on their polarity, different components in the mixture, which is to be separated will be absorbed at different levels. This is how the Thin Layer Chromatography process works.
Now, Column Chromatography
Another form of chromatography, which is equally popular is column chromatography. It is known as column chromatography because the separation process takes place in a vertical glass column. In this process, the mixture is moved down the glass column and the different components are easily absorbed by the stationary phase. The rate at which the components are separated depends on their affinity to the stationary adsorbent.
Difference between Column Chromatography and Thin-Layer Chromatography
Now that we have looked at two types of chromatography, let us try to understand the basic differences between the two. These differences will help us know why one form of chromatography is preferred over the other.
1) Thin-layer chromatography requires higher samples and lower analysis time. This is because the number of samples separated via TLC is much more than that done in the column chromatography process.
2) In Thin-layer chromatography, one makes use of strong reagents to identify the different components of the mixture. This works out well in comparison to column chromatography because the TLC plate can withstand strong solvents and colour creating agents.
3) The plates used in the thin-layer chromatography process are designed in such a manner that they can be heated to very high temperatures without undergoing any damage. This may not work out for Column chromatography plates.
4) Thin-layer chromatography is said to be more sensitive as there is less spreading of substance zones in this process in comparison to the column chromatography process.