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Topic: Thin layer chromatography experiment  (Read 9703 times)

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Offline Zamzen

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Thin layer chromatography experiment
« on: October 18, 2010, 04:53:11 PM »
Thin layer chromatography.
In one of my experiment involving thin layer chromatography we were supposed to separate different colorful compounds in spinach. These compounds are (structure is important)
Chlorophyll a http://en.wikipedia.org/wiki/Chlorophyll_a  color green
Chlorophyll b http://en.wikipedia.org/wiki/Chlorophyll_b  color green
Pheophytin a http://c14.dhigroup.com/pigments/structures/Pheophytin%20A.png gray
Pheophytin b gray http://www.angelo.edu/faculty/kboudrea/molecule_gallery/04_aromatics/chlorophyll-b_01.gif
B-carotene orange red http://en.wikipedia.org/wiki/Beta-Carotene
a xantophyll http://www.lookchem.com/300w/2009423/img/127-40-2.gif yellow
violaxantin gray http://en.wikipedia.org/wiki/File:Violaxanthin.svg
So the material was sand, spinach, sand and acetone which we mixed together and filtered and received spinach extract. Our thin layer was silicone gel which adsorbs polar compounds. We dripped 5-10 drops of the extract at a certain point and placed the layer in Petroleum ether (benzine) http://en.wikipedia.org/wiki/Petroleum_ether  mixed with acetone in the proportion of 3 benzine to 1 acetone so the height in the beaker was 0.5cm. we placed our thin layer with silicone gel and spinach there as well and these are the results.
http://i56.tinypic.com/15zfssw.jpg
. My conclusion is that polar compounds won’t travel so far with the benzine/acetone solution since the gel will create bonds with them that are strong and make it harder for them to move. On the other hand the nonpolar compounds will travel further since they only create van der Waals bonds with the gel compared to the hydrogen bonds the other compounds will create with the gel. I am a bit uncertain on this part and hope that you can correct me if I have done some mistakes.
So the orange red on the top is a-carotene. The gray one beneath it is violaxantin, the first green one is chlorophyll b because of its extra oxygen molecule, and after that chlorophyll a. the yellow color beneath that one is a xanthophylls and the gray ones beneath xantophyll is first Pheophytin b and then Pheophytin a. on the same reasons as my reasoning on the chlorophylls. Now the problem is that I have 2 extra yellow colors at the bottom which I don’t know how to fit in, in my conclusion. Perhaps they are compounds that are not important.
I’m thankful for any corrections about my reflections and conclusions.


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