Friday, January 23, 2015

The Specific Uses of Thin Layer Chromatography

Thin layer Chromatography is a process of first separating the compounds in a mixture and the suitably analyzing each one of them. The identity of each compound can be established along with their purity or concentration levels in the mixture. TLC chromatography is a very sensitive method and even the most micro quantities can be analyzed by this process. The time required for this separation and subsequent analysis may take between 5 – 10 minutes.

The Process Involved in Thin layer Chromatography

Generally, a three phased procedure is involved in the TLC. Firstly, the substance that needs to be investigated is dissolved in a volatile solvent that is easily evaporated that produces a very dilute solution. All along the separation process, photographs are taken regularly at all the different stages, which are often three in nature.

The first stage consists of spotting that uses a micro pipette in which a very small amount of the diluted solution is added and exposed to a thin layer of silica gel placed on a sheet of plastic. The solvent used evaporates quickly, leaving behind sediment that can be analysed. The next stage involved is the development stage where the TLC plate is introduced into a development solvent that moves up the plate by a capillary action. 

There are three polarities that interact with one another. The first is the silica gel plate which is very polar in nature, the next is the polarity of the solvent material, and finally of the sediment or the spot material that initially separated. The different distances the various components of the sediment moves at different speeds or distances and will be differentiated by the different spots that are formed. As the entire solvent moves up the plate and the spots are marked while the rest of the solvent is allowed to evaporate.

The final stage is the visualization stage where the silica gel plate contains a fluorescent material that can be easily read accurately as it glows under ultraviolet light. There is more than one method of visualizations to get more accurate results. When three spots are located, it implies that the mixture comprises three compounds.

Silica gel is one of the most preferred materials that are used in TLC chromatography. This is on account of its high polar nature and its affinity for bonding with hydrogen.