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July 22, 2025, 10:03:47 pm
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Author Topic: Chromatography  (Read 587 times)  Share 

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cohen

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Chromatography
« on: March 17, 2011, 08:37:55 pm »
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What exactly are the "mobile" phase, and "stationary" phase?
We started learning about it today (He did the theory for chapter 6 in today), and i have no idea what the hell half of the stuff means lol.
Cheers if anyones able to help me :)
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Ematuro

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Re: Chromatography
« Reply #1 on: March 17, 2011, 08:46:51 pm »
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The mobile phase is the solvent that passes through the stationary phase. The mobile and stationary phases differ depending on what type of chromatography.
Like in paper chromatography, the mobile phase is a solvent (the solvent depends on what you're analyzing) which could be methanol or alcohol or whatever. The stationary phase in paper chromatography is the paper which the solvent 'climbs up' on.
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luken93

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Re: Chromatography
« Reply #2 on: March 17, 2011, 08:49:34 pm »
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So in the example of seperating black ink in a pen, you need a "stationary" phase that different components of the ink (blue, green, red etc) will ADsorb to the surface. Some components will more strongly adsorb to the stationary phase, whereas others won't which gives us a seperation.

But to have this seperation, we need something to carry the ink up the stationary phase so that it can stick and unstick at different rates. This is where the mobile phase comes in, as it carries the mixture up the stationary phase. The mobile  phase will travel up faster than any of the components, and it is from this that we can calculate Rf (Retardation Factor) values, which are the distance travelled by the mobile phase / distance travelled by component.

Hope this helps
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2010: Business Management [47]
2011: English [44]   |   Chemistry [45]  |   Methods [44]   |   Specialist [42]   |   MUEP Chemistry [5.0]   |   ATAR: 99.60
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2012: MBBS I @ Monash

cohen

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Re: Chromatography
« Reply #3 on: March 17, 2011, 08:56:28 pm »
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I think I'm starting to get this.
So basically, the mobile phase is simply the solvent, and the stationary phase is the item that it's placed on (E.g. Paper, or a thin-layer plate coated with alumina).

The way my teacher explained it made it sound like they were phases that occurred during the chromatography process D:

Also, thanks for your explanations :)
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luken93

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Re: Chromatography
« Reply #4 on: March 17, 2011, 08:58:40 pm »
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Yep that's correct!

The thing that separates is the degree to which each component Adsorbs/sticks and desorbs/unsticks from the stationary phase.
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2010: Business Management [47]
2011: English [44]   |   Chemistry [45]  |   Methods [44]   |   Specialist [42]   |   MUEP Chemistry [5.0]   |   ATAR: 99.60
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2012: MBBS I @ Monash

cohen

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Re: Chromatography
« Reply #5 on: March 17, 2011, 09:07:50 pm »
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Oh my god, I can't believe I thought this was extremely hard when we were learning about it :|
I can't believe how simple this actually is :S
Again, thanks for your help :)
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