[spirochete]

I am trying to figure out why I got 2 seperate spots for a single compound after isolating it using thin layer chromatography.  The RF values were off by only 0.1 but there were 2 distinct spots. 

 It's  possible Wet filter paper touched the side of the plate at some point, causing the solvent to move spot side ways.  Another idea is that the plate was at a slant for part of the time it was developing; i think I adjusted it part way through. 

Would either of these things give 2 spots for a single compound in TLC?   

[sjb]

When you say you isolated it by TLC, do you mean you have purified it?

I don't think either of the ideas you have would cause two spots on the plate if it were a single compound, a smear perhaps, but not two distinct spots.

Is the compound stable to silica (or whatever stationary phase you've got on the plate)?

[spirochete]

The compound was given to me in pure form.  I'm also 99.9% sure it's stable with tie silica used in the plate.

[macman104]

So you got a pure compound, and ran a TLC on it, and got 2 spots, correct?  When you say it was given to you in pure form, was this someone else's "pure" form, and thus possibly not as pure as they thought it was?

Or, is it possible the compound has different conformers that have differing polarities?

Can you post the compound?

[spirochete]

I am guessing at this point it was my own sloppy technique that caused these weird results.  That's an interesting idea about 2 conformers with different polarities, but this is just lowly para amino acetyl phenol (tylenol), no possibility of different conformers.

[macman104]

Well, give it another shot.  If it still fails, I suppose you could ask someone else to try it.  If all that fails, I wouldn't doubt your own technique.  Alternatively, if you have access to a different analytical technique, like NMR, you could double check the purity...

[phil81]

What you could try is a 2D TLC. You take a square plate and spot the sample in one of the corners and run the TLC. Then, you rotate the square by 90 degrees and run it again.

If you see two spots, the sample contains 2 distinct compounds. If you see four spots, it could be due to conformers or decomposition on the silica.

[sjb]

I am guessing at this point it was my own sloppy technique that caused these weird results.  That's an interesting idea about 2 conformers with different polarities, but this is just lowly para amino acetyl phenol (tylenol), no possibility of different conformers.

Hmmm, another query. When you say your compound is tylenol, do you mean just paracetamol / acetaminophen, or the substance sold as Tylenol? Looking at http://en.wikipedia.org/w/index.php?title=Tylenol&oldid=218284092 it suggests there may be a mixture of active ingredients in there, like caffeine, or codeine on top, not to mention exipients and binding agents as well?

S