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2.2: Chromatography Generalities

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    93381
  • Chromatography is a technique used to separate the components of a mixture. It can be used as an analytical technique to gain information about what is present in a mixture, or as a purification technique to separate and collect the components of a mixture. Chromatography in the organic chemistry laboratory can be classified into several broad categories:

    Table with 3 different types of chromatography: On the left, Thin Layer Chromatography (T L C): analytical method for testing mixtures, in the middle, Column Chromatography: purification method for separating and collecting components, and on the right: gas chromatography: instrumental technique for analyzing mixtures.

    Table 2.1: Variations of chromatography.

    These techniques follow the same general principles in terms of how they are able to separate mixtures, and so will be discussed collectively in this section. Details specific to each technique will then be further discussed in their own sections.

    • 2.2A: Overview of Chromatography
      The first uses of chromatography involved separating the colored components of plants in the early 1900's. The pigments in a plant can be separated into yellow, orange, and green colors (xanthophylls, carotenes and chlorophylls respectively) through this method. The Greek name for color is chroma, and graphein is 'to write,' so chromatography can be thought of as "color writing."
    • 2.2B: General Separation Theory
      In all chromatographic methods, a sample is first applied onto a stationary material that either absorbs or adsorbs the sample: adsorption is when molecules or ions in a sample adhere to a surface, while absorption is when the sample particles penetrate into the interior of another material.

    Contributor

    • Lisa Nichols (Butte Community College). Organic Chemistry Laboratory Techniques is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. Complete text is available online.

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