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Dear freinds,
while working on a molecule i found papers published regarding the
analysis in which buffer was used both as solvent A (10mM ammonium
formate) and solvent B (organic part), but the organic part was
having the composition of 10mM ammonium formate in methanol, could
anyone suggest me what is the possible mechanism of using the buffer
in organic medium. Kindly help me in understanding the concept.
Thanks
Jacob.
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Hi,
That is commonly used in order to avoid any variation in buffer
concentration during the gradient.
If no buffer is added to the organic phase, buffer concentration might
be too low at the end of the gradient and thus unable to maintain the
desired pH.
In an isocratic method there is no reason for doing that.
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Jacob,
This is simply to keep the concentration of ammonium formate constant
during gradient elution. If you only put it in solvent A, the
concentration would be changing as the solventA/solvent B ratio
changes during the run.
Hope this helps.
Andrew
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Dear friend
This help ionization of molecules in LC-MS/MS
Dr Zafar
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The following message was posted to: PharmPK
I have not observed any significant difference either in chromatography
or in terms of sensitivity when I used organic phase with and without
additive (while analyzing tricyclic antidepressants).
I do not add additive to organic and still routinely achieve a
sensitivity of 10 pg on column, using normal HPLCMS.
It may be critical for some molecules for which presence of additive is
absolutely essential to achieve desired sensitivity.
I also feel that it could be just a force of habit carried from HPLC -UV
to HPLC-MS.
Regards,
Vinayak
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