Pictorial Guide to Thin Layer Chromatography, feat. Lego

Posted on Dec 16, 2011

In the several years that I tutored at the 1st-year help center, I’ve always had students who find thin-layer chromatography mystifying.  Most of these students don’t “get” what the plates are doing, or the role of the eluent.  For whatever reason, the physical analogy of things getting washed away and gripping the ground (or the inability to do so) seems to help in guiding the thought process.  I drew this up should you, as either instructor or student, would find this helpful.  Lo!  Behold the whimsical…

As usual, clicking on the figure opens a larger version for viewing.  A PDF version for print is available here. I’m not too happy with the final output – I feel as if the spatially-suggested connection between the analogy and the phenomena to be explained is not clear enough.  Suggestions to make this more useful / analogy more clear is appreciated.

Update (17 Dec 2011 Revision R3): The addition of the imagine/now consider label seems to clear up the analogy-phenomena.  I thank Loïc Samuel for the suggestion.

  • Loïc Samuel

    I think it’s a decent analogy, one that I’d never even though of before. I can see what you’re saying about there being a disconnect between the analogy. One possible solution is putting a frame around each section, the Lego panels with an “Imagine” label in the top left corner and a frame around the TLC lab section with a “Now Consider” label in the top left corner.

    On another note, there’s some work that could be done on subject-verb agreement. For example, “When a wave comes rushing in, everyone get washed […]” should be “When a wave comes rushing in, everyone gets washed […]”.

    Also “further” is for figurative distance while “farther” is for physical distance. So the text should read “Some go farther” instead of “Some goes further”; “The mutants […] get washed much farther” instead of “The mutants […] get washed much further” etc.

    Hope it helps.

    • Jon

      Hi Loïc – Good idea! I tried out your suggestion and it seems to work quite well. I think part of the trouble in the spread is that the imaginary part is more colorful and vivid than the real part. I’ve added an additional graphical indicator in the – – – dash lines for the imaginary world and —- solid lines for the real world. We’ll see how others feel about this.

      As to conjugating verbs… that’s sadly not one of my competence. (I blame it on my mother tongue not “doing” conjugation.) On that note, quite disastrously, I’m now learning Latin, where nouns, adjectives, and verbs all have to be conjugated… -.-

      So! This wasn’t something I could have picked out on my own, and many thanks for your help with that.

      • Loïc Samuel

        I’m glad I could help. I think the labels work really well, and the use of solid and dashed lines does help differentiate between the whimsical and the concrete

  • I, too, once came up with an analogy for chromatography, and it works “ok” for all types of chromatography


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  • Lemons

    What program did you use to make this? What font is it in?