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Topic: A simple question about cation-exchange chromatography  (Read 2738 times)

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Offline wtolf2

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A simple question about cation-exchange chromatography
« on: April 23, 2013, 05:36:32 AM »
Which will come out first through the column? Aliphatic or Aromatic amino acid?
They are uncharged!!

Offline Babcock_Hall

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Re: A simple question about cation-exchange chromatography
« Reply #1 on: April 23, 2013, 08:56:16 AM »
Is this a homework problem?

Offline wtolf2

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Re: A simple question about cation-exchange chromatography
« Reply #2 on: April 23, 2013, 10:22:48 AM »
Yes it is. Any idea?

Offline Arkcon

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Re: A simple question about cation-exchange chromatography
« Reply #3 on: April 23, 2013, 10:40:00 AM »
What can you pull together for an answer given their structures.  You seem to know that there's no obvious charge to cause binding, but can you come up with other effects that would slow one or the other?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline wtolf2

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Re: A simple question about cation-exchange chromatography
« Reply #4 on: April 23, 2013, 11:45:09 AM »
Yeah there is no other effect affects the order of amino acids coming out. It seems there is no answer...

Offline Babcock_Hall

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Re: A simple question about cation-exchange chromatography
« Reply #5 on: April 23, 2013, 01:10:02 PM »
One, you need to show your attempt first before we can help with homework (Forum rules).  Two, you have not provided any information about pH or what matrix is employed, which would be helpful.  Three, there are other effects besides pure ion-exchange that sometimes come into play.  In my experience it depends on the matrix, however.

Offline Arkcon

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Re: A simple question about cation-exchange chromatography
« Reply #6 on: April 23, 2013, 01:29:35 PM »
Well, for practical applications, you'll have to consider the matrix supporting the cation-exchange group, and the size of the pores vs the size of the molecules.  But for a homework question, looking for some sort of transient phenomena would be what's needed to answer the problem
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Babcock_Hall

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Re: A simple question about cation-exchange chromatography
« Reply #7 on: April 23, 2013, 04:28:48 PM »
@OP, At low pH values, the amino acids will not be uncharged.  What charge will they have?

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