Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1]   Go Down

Author Topic: Amino acids on TLC plate Question  (Read 16910 times)

0 Members and 1 Guest are viewing this topic.

Jazzified

  • Regular Member
  • ***
  • Mole Snacks: +1/-0
  • Offline Offline
  • Posts: 42
Amino acids on TLC plate Question
« on: January 27, 2008, 04:24:23 PM »

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!
Logged

AhmedEzatAlzawalaty

  • Full Member
  • ****
  • Mole Snacks: +4/-31
  • Offline Offline
  • Gender: Male
  • Posts: 191
Re: Amino acids on TLC plate Question
« Reply #1 on: May 09, 2008, 09:58:28 AM »

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

zerokun

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 12
Re: Amino acids on TLC plate Question
« Reply #2 on: May 26, 2008, 04:37:08 AM »

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.
Logged

Mitch

  • General Chemist
  • Administrator
  • Sr. Member
  • *
  • Mole Snacks: +371/-8
  • Offline Offline
  • Gender: Male
  • Posts: 5180
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re: Amino acids on TLC plate Question
« Reply #3 on: May 26, 2008, 12:36:34 PM »

I would of thought that in normal phase chromatography of TLC, Silica being a common stationary phase, the stationary phase is rather polar.
Logged
Most Common Suggestions I Make on the Forums.
1. Always start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

zerokun

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 12
Re: Amino acids on TLC plate Question
« Reply #4 on: May 26, 2008, 02:31:02 PM »

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 .
Logged
Pages: [1]   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.071 seconds with 24 queries.