[bettyyy]

The question I have is if I were to be performing a (TLC) thin layer chromatography, and these compounds were dissolved in a nonpolar organic solvent; then subjected to silica gel column where more polar solvent would be added progressively.  What would the order of elution be and why?


What I do know... or I think I do, is
-reason of order or elution is because the components with the greatest affinity for the move phase travel up the plate faster than those that have greater affinity for the stationary phase.  This depends on the polarity of the molecule’s, as the least polar organic molecules will not “stick” to the silica gel as well and therefore they elute first. 

and I have the order of polarity:
Amide > Acid > Alcohol > Ketone > Aldehyde > Amine > Ester > Ether > Alkane

okay, so I know that amoxicillin has an amide, so that will elute last because it's more polar.
aspirin will elute third because it is an acid

THC is non polar, so I would say that that elutes first, but I am unsure because of the methamphetamine has an amine functional group, and THC has a phenol ring.

Am I on the right track... or did anyone understand what I'm talking about?  If so, please *delete me*  Thanks in advance.

[sjb]

Sounds reasonable, but what if you have a relatively polar acid, e.g. acetic acid and a relatively non-polar amide, such as paracetamol.

In practice, the only way to be certain is to run the TLCs yourself and find out.

Also, perhaps as an aside, what happens if you have reverse-phase silica?