[Jazzified]

On a cellulose TLC plate with the solvent being N-butanol/HOAc/water (4:1:1), I have to order the following amino acids from the one that will travel the highest on the plate to the one that will travel the least: Gly, Phe, Ala, Pro, Leu.

I ordered the amino acids: Leu, Pro, Ala, Phe, Gly, based on their hydropathy index values (more negative to more positive values).  Is this correct?

I also have to explain why the amino acids would separate on the TLC plate in regards to the type of chromatography system (normal or reverse phase), and I would like some help explaining this.  Thanks!

[AhmedEzatAlzawalaty]

solvent medium (acid, neutral or basic) affect the elution of amino acids
because they are amphoteric.

[zerokun]

Hi, this is my first post here ,so if any mistake pls tell me

the polarity of a particular amino acid is dependent on the number of charges and the charge of an amino acid is dependent on pH.

In normal phase TLC chromatography, the stationary phase is less polar than mobile phase. You already know that in non-polar stationary phase, amino acids that are less polar will move farther than those more polar.
And, the more non-polar substance, the more the substance will be hydrophobic.
So, your order of amino acids should be right . ( because non-polar move the farthest in non-polar normal stationary phase)

I not really sure about how to explain the separation of amino acids in regards of chromatography system, but i think the normal phase would be good to separates non-polar amino acids and the reverse phase would be good separates polar amino acids.

i hope this will help u.

[Mitch]

I would of thought that in normal phase chromatography of TLC, Silica being a common stationary phase, the stationary phase is rather polar.

[zerokun]

My biochemistry book wrote :"the stationary phase is the silica" but the following page it said the water held in cellulose is the stationary phase and the mobile phase is the solvent .

And, i remember my lab demonstrator told me that stationary phase in TL cellulose chromatography is less polar than solvent. 
But, as u said, i think that silica should be rather polar

I am confused now .