About Organic Chemistry 1.5b

By Docta · Nov 1, 2011 · ·
  1. Docta
    Chromatographic purity (paper and thin-layer)

    In paper chromatography a small sample of the substance to be analysed is put onto the bottom of a strip of filter paper, the sample end is dipped into solvent and the solvent migrates up the paper by capillary action. The sample travels up the strip behind the solvent front to form a single spot if pure or a string of spots corresponding to the impurities. Reagents are sometimes sprayed on the strip to aide examination and identification.

    A similar reagent purity test is thin-layer chromatography.
    A paint made of silica gel is prepared then applied to a glass plate to create a thin absorbent film that is 0.25mm when dried.
    As with paper chromatography samples on the plate are developed by solvents then inspected for spots that would correspond to known findings or indicator reagent can be applied as a fine mist to reveal more information.


    The most attractive elements of paper and thin-layer chromatography are it’s sensitivity allowing the analysis of samples down to 1 microgram and ease of data collection for comparison, rate of travel, reaction to reagents, amount and spacing of spotting, all easily visible with out special equipment.

    This has been a quick summery of chromatography and the purity control needed in quantitative analysis.

    I know this is not what people wont to read when they ask to learn organic chemistry but if you wont to be a mechanic it helps if you know how to drive the car.
    That being said I’ve found talking of this chemistry boring and unrelated to anything I’m working on. I think we may look at some other area.

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  1. Pharmac0therapy
    Agreed, its not what most members will care for reading about, but definitely an essential elementary skill in the art and science of organic chemistry. Kudos for enlightening the readers.
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