thin layer chromatography

[JackBean]

Hi,
I just want to make sure I have it correctly, before I'll say the students they are wrong
Anyway, we are doing TLC with extract from red pepper, the stationary phase is silufol (Al2O3) and the mobile phase is benzene. Thus the more hydrophobic pigment, the further it should travel, right? Thus like beta-carotene should be first and some hydroxylated xanthophyls should stay at start, right?
thx

[jonmoulton]

Hi Jack,

I agree, though the xanthophylls might move a little. pi clouds might give some affinity with the conjugated mobile phase (benzene).

- Jon

[JackBean]

Hi Jon,
thanks. It's just weird, because they have some orange pigment, which stays just on the start, while something bright yellow is right at the front

[jonmoulton]

If you've easy access to a UV-Vis spec, you could scrape off the bands, elute them and take some spectra -- then assign the kids into the literature to find likely candidates. It could get complicated if some pigments are co-migrating, but it would also be fun to see if the students come up with that possible explanation.

[JackBean]

nice