• Question: What is the basic idea behind chromography paper ?

    Asked by deirbhileok to Enda, Jean, Kate, Kev, Tim on 18 Nov 2012.
    • Photo: Tim Downing

      Tim Downing answered on 18 Nov 2012:

      Hi Deirbhile,

      I presume you mean chromatography? This is the separation of unknown liquid in other known mixtures to determine its components, eg paper and a solvent. So for paper chromatography the unknown liquid is placed at one end of the paper (the stationary part), and a solvent like dilute alcohol is placed at this end so that it travels up the paper, dragging some of the unknown substance with it. The tendency of the unknown substance to be dissolved reflects the chemistry of its constituents. So to measure this we can place known substances on the paper as well.
      You might also try the scientists in the Hydrogen Zone, they might have more information for you!
      Tim

    • Photo: Jean Bourke

      Jean Bourke answered on 19 Nov 2012:

      Chromatography paper is basically filter paper. It needs to be quite absorbent and not fall apart when it gets wet.

      Chromatography involves putting a bit of the sample to be analyzed on a stationary phase (the paper) then using a mobile phase (usually water) to separate the components and pull them along the stationary phase.

      Chromatography is used analytically: to determine what is in a mixture, to compare 2 samples to see if they are the same.
      It can also be used preparatively. In preparative chromatography you just cut out the bit of the stationary phase (paper) that has the thing you want on it and wash it off the stationary phase (paper).

      We use chromatography all the time in the lab to see if your reactions have worked and to check if our compounds are pure. It’s really fast, easy and safe.

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