Thin layer chromatography is a type of liquid chromatography that is used to separate non-volatile mixtures such as glycerine into its individual components. The process is performed on a sheet of glass, plastic, or aluminium foil coated with a thin layer of adsorbent material like silica gel, aluminium oxide (alumina), or cellulose (known as the stationary phase).
However, TLC is utilised in many industries for different purposes. Here are the applications and advantages of the technique.
Various applications of thin layer chromatography (TLC) are:
- Test the purity of the sample: Thin layer chromatography helps to detect the purity of the sample by direct comparison with the standard or authentic sample. Any impurity in the sample shows up as extra spots in chromatography.
- Identify the components: Thin layer chromatography can purify, isolate and identify the natural products like volatile oil or essential oil, fixed oil, waxes, terpenes, alkaloids, glycosides, steriods etc. in the test samples.
- Examination of reaction mixtures: When you combine two or more substances and the resultant combination shows a change in the structure or energy content of the interacting entities, the final product is called a reaction mixture. When such a mixture is subjected to thin layer chromatography, it can tell whether the reaction is complete or not and also check other separation and purification processes like distillation, molecular distillation etc.
- Biochemical analysis: Biochemical metabolites from the body fluids, blood plasma, serum, urine etc. can be isolated using thin layer chromatography.
- In chemistry, TLC is used to separate and identify closely related compounds or cations and anions in inorganic chemistry.
- Pharmaceutical industries utilize TLC technique for qualitative analysis or detect impurities in various medicines like hypnotics, sedatives, anticonvulsants, tranquillisers, anti-histaminics, analgesics, local anaesthetics, steroids, etc. Yet another important application of TLC is to separate multi-component pharmaceutical formulations into its individual components.
- In food and cosmetic industry: Any artificial colour, preservatives, sweetening agent, and other impurities in food and cosmetic products can be detected and isolated by TLC technique.
What are the advantages of thin layer chromatography (TLC)?
The technique gains an upper hand because:
- It requires less equipment.
- The separation of components is faster, thus, saving time.
- The technique is highly sensitive and gives more accurate results.
- The lower detection limit of analytical sample in TLC is approximately one decimal lower than that of paper chromatography. Further, TLC requires very small quantities of a sample to analyse and give results. This proves cost-effective for labs facing scarcity of funds.
- In TLC, you can spray corrosive agents to identify the sample, but this is not possible in paper chromatography as cellulose gets destroyed.
- Adsorption, partition, and ion exchange chromatography also utilise this technique as wide range of adsorbents are available.
- The individual samples do not get diffused as in paper chromatography.
- TLC separates the sample into its individual components. These components can be recovered easily by scratching the powdery coating of the plate. Moreover, quantitative separation of spots is possible with TLC.
- You can see and identify the individual components by UV light as the inorganic adsorbent background does not fluoresce.