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Offline fluorescence

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question about HPLC
« on: 07/10/2005 12:56:08 »
Hey all,

I did a simulated HPLC experiment, and I'm just wondering if my results are correct.

experiment details -
compounds: phenol, p-nitrophenol, p-cresol and methylbenzoate

elution mode: gradient elution - initial 40% methanol 60% water, final 100% methanol

stationary phase: hydrophobic (not sure exactly what it is)

we had to do 3 individual components separately to confirm their identities in the chromatogram with all components; and from my graphs it appears that phenol had the smallest retention time, then nitrophenol, then cresol
... isn't nitrophenol more polar than phenol, so then wouldn't it be eluted first?

any help would be appreciated :)


 

Offline Ylide

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Re: question about HPLC
« Reply #1 on: 08/10/2005 19:21:13 »
Polarity of a compound affects retention time, but is not the only factor, size, shape, and orientation of functional groups affect it as well.  But aside from that, the resonance intermediates of nitrophenol would serve to stabilize (i.e. delocalize the charge) the molecule, effecting a greater retention time in a hydrophobic stationary phase.





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Offline fluorescence

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Re: question about HPLC
« Reply #2 on: 10/10/2005 04:27:32 »
oh.. ok that makes sense
Thanks!
 

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Re: question about HPLC
« Reply #2 on: 10/10/2005 04:27:32 »

 

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