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Author: Subject: Retention factors of some compounds
SecretSquirrel
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[*] posted on 20-3-2007 at 10:51
Retention factors of some compounds


I'd be very grateful if somebody could tell me the retention factors for these three compounds: paracetamol, propiphenazone, caffeine. I searched Merck index and some web pages, but I can't seem to find these information. I unfortunately don't have access to any other literature.

Thanks in advance.
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matei
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[*] posted on 20-3-2007 at 11:07


I assume you mean chromatographic retention factors. Before trying to find those in the literature you might find quite useful to read some basic facts on chromatography in general (try wikipedia).
The retention factor does not depend only on the particular chromatographic method you are using (e.g. HPLC, GC, TLC etc.) but also on the stationary phase and mobile phase. Retention factors are only valid for a specific method-stationary phase-mobile phase combination.
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Nicodem
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[*] posted on 20-3-2007 at 11:59


There is only one useful source of such information. You need to perform the chromatography on each of the three compounds on the system you intend to use.
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SecretSquirrel
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[*] posted on 21-3-2007 at 00:16


Thank you Matei and Nicodem. I didn't know the result depends on the selection of stationary and mobile phases. I already performed TLC on a sample and have even calculated the retention factors so I just wanted to make sure if I got correct results for these compounds.

[Edited on 21-3-2007 by SecretSquirrel]
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matei
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[*] posted on 21-3-2007 at 10:05


SecretSquirrel,

Usually these retention factors are not reproducible so they are rarely reported in the literature. If you want to correctly identify these substances you should try a specific reagent for each one and dip the TLC plate in it - the spot corresponding to that substance will become coloured.
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