I have been using 0.02%conc. HCl v/v in place of TFA,for the past four to
five years.It works like a charm.Considering that dilute halides can affect
stainless steel,I keep that in mind,and I do not let anything in the acid.
I have no idea why I used 0.02%,and I am adding it also to solvent B,which
is 90%acetonitrile.I remember that way back when Waters Associates,I
think,suggested the use of 6mM HCl in place of TFA,which is about right for
0.02%.
Unless you rust up your system,HCl is completely transparent.
Fulvio Perini
UNMC
986805 Nebraska Med.Cntr.
Omaha,NE 68198-6805
John.Holt@aventis
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The blank chromatogram on the 1090 LC of our HP G1000 Sequencer System has
a slope from 0 to 6mAU over the needed part of the separation. This slope
appears to have increased steadily over a year or so. As others have
remarked, the price of this is loss of sensitivity, which is now nearer
10pmole than the 1pmole that was previously possible. If this were simple
rp HPLC, I would match the absorbances of mobile phases A and B
experimentally by adding TFA to A (currently, B absorbs more than A).
Can anyone tell me (a) if I'm right in thinking that the problem is no more
than absorbance mismatch, (b) if there's an acceptable fix (doesn't require
extensive re-tuning of PTH separation) and (c), if there's a better (more
inert, or MS-friendly) chromophore to use than TFA to match solvents in rp
HPLC?
John Holt
Analytical Sciences
Aventis Pasteur
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