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Topic: HPLC!  (Read 6440 times)

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socomplicated

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HPLC!
« on: January 07, 2005, 10:00:44 AM »
from my book it says:

The chemical interactions of the mobile phase and sample, with the column, determine the degree of migration and separation of components contained in the sample. For example, those samples which have stronger interactions with the mobile phase than with the stationary phase will elute from the column faster and thus have a shorter retention time, while the reverse is also true.

what do they mean when they say "while the reverse is also true." ? ???

hope very much for ideas!

thanks!


socomplicated

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Re:HPLC!
« Reply #1 on: January 07, 2005, 07:12:12 PM »
does anyone know what it means?  :(

Offline Mitch

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Re:HPLC!
« Reply #2 on: January 07, 2005, 09:28:46 PM »
that samples which have weaker interactions with the mobile phase than with the stationary phase will elute from the column slower and thus have a longer retention time, while the reverse is also true.
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socomplicated

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Re:HPLC!
« Reply #3 on: January 08, 2005, 09:41:33 AM »
that samples which have weaker interactions with the mobile phase than with the stationary phase will elute from the column slower and thus have a longer retention time, while the reverse is also true.


thanks Mitch, but i still have not got the answer i am looking for. what kind of interaction is "the reverse" ? anyone has an idea here or my book goes crazy? thanks!

Cris

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Re:HPLC!
« Reply #4 on: January 11, 2005, 08:12:14 AM »

Hello, "socomplicated"

Well, let's see...I think you're only complicating things...LOL... It's very simple, and I believe that Mitch already answered your question:

First: compounds that have stronger chemical interactions with the stationary phase than with the mobile phase will be more retained in the column, having a greater retention time.
Second (the reverse of the first sentence): compounds that have weaker chemical  interactions with the stationary phase than with the mobile phase will be less retained in the column, having a shorter retention time.

This difference in chemical interactions between two compounds allows their separation by retention times in the column.
Look, "the reverse" here only means that the compound has a greater or smaller interaction with the stationary phase. But in terms of chemical interaction it is the same, such as partition/adsorption interactions, for example.
I hope I could help you to clarify your doubt...or...did I make you get more confused? LOL.

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