Chromatography

[jaydee]

I read that Thin layer Chromatography (TLC) is best used for non polar compounds. the 2010 VCAA u3 exam q6 of MC asks which Rf value represents the polar compound moving through the stationary phase and it happens to be the smallest Rf value. What am I not seeing? I thought polar compounds are less adsored onto the stationary phase of TLC hence it will be a high Rf value. VCAA says that polar substances are most attracted to the polar stationary phase! im confused :S is TLC for polar or non polar substances?

[REBORN]

Yes polar is more attracted to polar as it follows the rule like attracts like/like dissolves like.

TLC can be used for either as long as the stationary phase and the substance are of the same type (AS FAR AS I KNOW --> wait for confirmation)

[jaydee]

it's a bit confusing. both heinemann and nelson say it's more suitable for less polar compounds...

[REBORN]

Indeed. I think however the q specifies polar stationary phase and polar component hence lower Rf value...

[jaydee]

yeah thats fair enough since it does say polar stationary phase.  trippy question though since the emphasis on the difference between paper chromatography and TLC is that PC is for polar and TLC is for non polar (usually) 

[illuminati]

Yeah, just because TLC is more suitable for less-polar compounds doesn't mean that polar compounds can't be analysed altogether.
In which case, its been given that it is a polar stationary phase, therefore the most polar compound would adsorb the strongest to the stationary phase, and have the lowest Rf value.