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baseline negative

http://www.chromforum.org/viewtopic.php?t=10153

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baseline negative

Posted: Fri Mar 06, 2009 9:32 am
by RAMESH JANGA
Dear all
Please give me suggestion for baseline is observing nagative during gradient by using following conditions

Column: Symmetry C8 250x4.6mm 5u
Wavelength:230nm
Flow:1.0ml/min
Solvent-A: 0.1% TFA in water
Solvent-B: Methanol: Acetonitrile(80:20)
Gradient
time/%B: 0.01/35,3.0/35,30/80, 40/90,45/35,50/35.


regards
ramesh

Posted: Fri Mar 06, 2009 11:22 am
by Csaba
Hi,
TFA in mobile phase A absorbs light at 230 nm.
Either accept a sloping baseline or add some TFA to your mobile phase B.

Posted: Fri Mar 13, 2009 2:45 am
by mohan_2008
on the contrary,

I think the MeOH in B solvent is absorbing.

Posted: Fri Mar 13, 2009 10:16 am
by HW Mueller
It seems obvious that the absorption of TFA is the predominant factor here.
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