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Why Chromatography?


Chromatography is a very important technique in chemistry. The reason is that it can separate one type of molecules from others. In this section you will learn how this is accomplished.


Basic separation mechanism


The basic mechanism for the separation is that different kind of molecules will adsorb ("stick") to different degrees to a solid particle. The separation process is explained and visualised in the Chromatographic Principle


The principle for chromatography is used in many different modes. Thin Layer Chromatography (TLC) is a simple and quite often used mode. This is nicely illustrated in the movie by James K. Hardy. A technique that resembles TLC is paper chromatography. A good illustration of it is found in the site from University of Guelph that illustrates the use of chromatography to identify the components in a mixture of unknown composition.


How to regulate the separation


The tendency for a certain type of molecules to adsorb to the stationary phase varies with the properties of the mobile and stationary phase, respectively. An illustration of this important fact is found in the educational site by Dan Damelin.


A large number of stationary phases are available and the composition of the mobile phase can be varied indefinitely. To select the most appropriate mobile phase in combination with the best stationary phase for a certain mixture, is one of the important skills needed of those that works professionaly with chromatography.


What is HPLC?


There is a large number of chromatographic techniques. By far the most important and common of them all is HPLC (High Performance Liquid Chromatography). A description of the HPLC instrument and an animation of its principle is found under the section HPLC instrument.


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