Chromatography

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Chromatography
Chromatography was developed by Mikhail Tswett, a russian botanist, in 1903. He produced a colorful separation of plant pigments through a column of calcium carbonate. Chromatography has since developed into an tool for separating and identifying compounds. An example is water and ink on paper. It is seperating out a mixture of chemicals. In order for chromatography to work, one solution in the mixture has to be in one state of matter moving over the surface of something else in another state of matter that stays where it is. The liquid, which is the ink, is dissolved in water or another solvent on the surface of a solid, the paper. The moving substance is called the mobile phase and the substance that stays put is the stationary phase. As the mobile phase moves, it separates out into its components on the stationary phase.

Chromatography works because when the liquid moves past the solid, some molecules are stuck on the surface. These molecules are stuck until the liquid they came from pulls them back. This is also called adsorption. This is different than absorption because that is where the molecules are permanently trapped with the solid. Different liquids go through different adsorption processes because each liquid molecules spend longer time on the solid. In the image below, the green molecule will move faster since it spends more time in the liquid. The yellow will go a bit slower, and the red molecule will be the slowest because more molecules get stuck.



There are three main types of chromatography. Gas, paper, and column. Paper chromatography occurs when the stationary phase is paper. This experiment usually involves ink and water. Column chromatography is when the stationary phase is a vertical glass jar. This jar is highly packed with an adsorbent solid, such as of silica gel, or a solid coated with a liquid. The mobile phase is pumped at a high pressure through the column and splits into its components, which are then removed to be analyzed. Gas chromatography is one of the most commonly used techniques. It is a column chromatography, but using gas as the mobile phase. A machine, called a gas chromatography machine, was created just for this purpose.
 



Chromatography is used to better understand what we eat, what chemicals we put on our skin, and the medications we take. Chromatography is even used in space. Because it is so important in our life, it can help detect other building blocks of life in space. It can help us discover new species or even a new habitable planet. The future of chromatography is so important because of how much our life depends on it.





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