I am looking into using paper chromatography to distinguish between standard drugs and counterfeit drugs for my high school research project. I have decided on using aspirin as the "standard" drug and I plan to make my own counterfeit versions of aspirin by preparing a solution of aspirin and adding in other chemicals (eg. salicylic acid). I've tried searching online for "how much" analyte I should be using for the paper chromatography, but all I can find is the instruction of "spot the paper with the solution".

Two questions:

  1. Does anyone know resources for me to get highly specific instructions on paper chromatography (most sources only talk about TLC)
  2. What concentration of aspirin or the "counterfeit aspirin" should I use to spot the filter paper
  3. Would placing an iodine crystal beside my filter paper do anything (I read that iodine is highly reactive with aromatic compounds, and can produce stains, but using iodine was suggested for TLC, so I'm not sure if it works for paper chromatography too)

I'm not sure if the following affects the concentration of analyte I should be using, but I will list them just in case they do:

  • I am using 95% ethanol as my mobile phase
  • I plan to use UV light (roughly 229 nm) to visualize the developed filter paper

And if you're wondering, I can't perform column chromatography or TLC because my school doesn't have a column or silica gel (so no plates either). I also have to get the experiment done in 3 weeks at max, so I don't think I will have the time to order the required instruments.

I just began researching chromatography last night, so I'm not the most confident about my experimental design. So, if you find something odd about my experimental design anywhere, please point it out. Thanks.

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    $\begingroup$ Have you watched Youtube videos on paper chromatography just for a general idea? Don't worry about the exact concentration. What I would suggest is that you make a relatively concentrated solution (1/3 of a spatula) in 4-5 mL of your mobile phase, ethanol in your case. Using a narrow capillary spot the paper. Using a too dilute solution of aspirin may make the visualization difficult. $\endgroup$
    – AChem
    May 31, 2022 at 4:10
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    $\begingroup$ Ideally use the same concentrations as suggested for TLC. chembam.com/online-resources/experiments/… $\endgroup$
    – AChem
    May 31, 2022 at 4:11
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    $\begingroup$ You also need to try different solvents not just one of different polarities. There will be trial and error involved here. $\endgroup$
    – AChem
    May 31, 2022 at 4:13
  • $\begingroup$ You will have to experiment and go to the lowest convenient amount with good enough detection result. Too big amounts negatively affect the spot separation, cause strong diffusion and large spots. // Not from paper chrom, but as a rough idea of a first shot: When I used to work with CAMAG HPTLC UV scanners, mostly on silica plates, we used progressively spraying/drying typically several microliters of 1% solution, to determine "chromatographical purity" in order of 0.x%, using extinguishing of fluorescence of fluorescent indicator in the plate. $\endgroup$
    – Poutnik
    May 31, 2022 at 9:58


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