What is Thin Layer Chromatography?
Similar to Silica Gel Chromatography, Thin Layer Chromatography is another procedure used to separate individual components from a mixture. Thin Layer Chromatography also consists of a solid or stationary phase like a silica gel plate and a mobile phase. The Silica Gel acts like an adsorbent for thin layer chromatography. The mobile portion can be a solvent or a solvent mixture, which moves upwards using capillary action. The components that are to be separated are adsorbed at different levels and finally collected at the lower end of the Thin Layer Chromatography or TLC plate.
How the TLC Procedure Works
In Thin Layer Chromatography, first a small quantity of the solvent mixture is inserted into a developing vertical glass column. The solvent mixture must be to such an extent that the mobile portion sits separate from the samples placed at the bottom of the plate. In the next step, place the silica gel plate in the developing vertical column and cover it completely. After some time, the capillary action will take place thus starting the separation process. For better results, one can also place filter paper soaked in the solvent inside the vertical column. Both these steps, the closure of the column and the placement of the filter paper, go a long way in securing the solvent’s presence in the column.
One has to next wait for the solvent to rise to 1 centimeter below the top of the TLC plate and when this happens, remove it from the glass column. The plate will be dry in some time and if the chromatography process is a success, spots will appear on it. The separated components are then taken away for different uses.
Applications of TLC
Thin Layer Chromatography has many uses in varied fields like pharmaceuticals, traditional medicine, insecticides, pesticides among others. The uses are explained in detail below:
1. In Pharmaceutical Industry: TLC is widely utilized in the pharmaceutical industry. It is mainly used as a means to find out the low levels of impurities present in medicines. In this process, the medicinal substance is administered on the TLC plate and after chromatography, secondary spots appear on the plate. These spots are compared for parameters like size and intensity with earlier spots of smaller loadings of known impurities. The latter underwent a similar chromatography process earlier.
2. In Traditional Medicine: Traditional medicines make extensive use of plant extracts. In order to know what constitutes these plant extracts, the process of TLC proves very useful. When the samples of a plant extract are separated using TLC, a clearer understanding of the components of the plant can be arrived at. This procedure is also used to study plants of the same species but grown in different environmental conditions.
3. In Pesticides: In the pesticide industry, TLC has great importance. It is uses to separate identify and determine the different components of high-grade pesticides. This method is also used to segregate metabolites or enzyme inhibitors.