Chromatography is a method used in the laboratory to separate a mixture of different components. There are two different phases in this technique. The mobile phase refers to the solute compound, which moves along the stationary phase, which does not move. As the mobile phase passes through the stationary phase, each component in the mixture flows at different speeds according to its affinity and is absorbed in the stationary phase. This fundamental principle changes according to gas chromatography, ion exchange, affinity, etc. Many complicated components can be distinguished easily and quickly with chromatography. It can even differentiate components with similar properties. It detects drugs, alcohol, or any form of volatile substances present in the blood.
Types of Chromatography
This method has been employed in the field of science for various purposes. There are different types of chromatography attesting to varied requirements. Some of them are as follows,
- Gas chromatography
- Column chromatography
- Paper chromatography
- Liquid chromatography
- Thin-layer chromatography
Gas Chromatography :
This method is entitled to separating or adsorbing volatile or harmful gases. This technique is suitable for components with high volatility, low molecular mass, thermally stable properties. The standard mobile phase in this method is Gas. The stationary phase can be solid or liquid. Helium is used to move the mobile phase.
Gas chromatography is used in pharmaceuticals, forensics, alcohol detectors, and so on.
2 Type of Gas Chromatography :
- Gas-Liquid chromatography (GLC)- where the liquid is the stationary phase
- Gas-Solid chromatography (GSC)- where solid is the stationary phase.
This method is also employed to separate components or remove impurities. The stationary phase used here is solid, which is inexpensive but possesses qualitative adsorption properties. When the mobile phase passes through, the components with less affinity move fast and can be collected first from the column; the high absorption component will move slowly and can be eluted only in the end. This method is used in food, beverage, chemical, forensic industries.
Types of Column Chromatography
- PARTITION COLUMN CHROMATOGRAPHY – liquid is used in both mobile and stationary phases.
- GEL COLUMN CHROMATOGRAPHY – Gel (solvent) is used as the stationary phase.
- ION EXCHANGE CHROMATOGRAPHY – Ion-exchange resin is used in the stationary phase.
Paper Chromatography :
This method uses partition and adsorption techniques. These are mainly used to detect contaminated foods or beverages, cosmetics, consumption of drugs in animals and humans. This chromatography is done by first choosing suitable paper or strips and filters. Once the sample is spotted on the sheet, it is dipped in the mobile phase, and it moves with the help of chromatogram development. Paper chromatography was the primary method used back in 1855. It is categorized as follows,
Types of paper Chromatography
- Ascending paper
- Descending paper
- Ascending – Descending
- Radial or circular
- Two Dimensional
Liquid Chromatography :
In this technique, a solid stationary phase is used, and the mobile phase is liquid. It is commonly used to separate molecules, acids, proteins, and many more. Each component has varied absorption, partitioning, ion exchange, size, and momentum, which interferes with the stationary phase and gets distinguished. This is used on a small scale to isolate and remove contaminants from any mixture. High-performance liquid chromatography is available with the pressurized granular absorbing stationary phase in many laboratories and medicinal research centres. It also includes other types,.
Types of Liquid Chromatography
- Normal phase
- Size exclusion
- Aqueous normal phase
Thin Layer Chromatography :
This procedure is an upgraded version of paper chromatography. As the name suggests, this method functions on the surface of mediums like plastic, glass, aluminum foil. On top of that, a thin layer of absorbent is coated. Commonly used absorbent layers are aluminum oxide, cellulose, and silica. Once the sample spots are marked in the layers, the plate is placed inside the chamber, and the solvent or the mobile phase is emptied into the chamber. The components get segregated with their diverse retention factors. This type is used in food, beverage, medicinal, cosmetic industries, analyze natural resources like oils, volatiles, alkaloids, and so on.
Chromatography Application :
- All these methods are used in pharmaceutical, research, broadly in science sectors. It evaluates different substances, detects adulterants, removes contaminants.
- It helps in qualitative and quantitative examination of water. Also exposes certain harmful volatile gases with the help of Gas chromatography techniques.
- It is utilized in food and beverage for nutritional standard verifications. Also detects any form of contaminants and added preservatives.
- It is applied in forensic science to detect and analyze crime scenes, blood, or hair samples collected, which may lead to some possible clues.
- It can separate mixed components, remove impurities in an analysis.
- One can derive satisfactory analysis, purification, and separations.
- It is cost-efficient and requires only a small amount of samples.
- Also, this technique is adopted in molecular studies and research institutions to examine proteomics, nucleic acids.
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