>We are having problems with 'ghost' -peaks that are appearing in are RPC
>runs. We are using a spheri-5 rp-18 column with a precolumn ( rp-8)
>The buffers are:
>A: 0.1M Triethylamine (TEA, >99%) in HPLC-grade water brought to pH7 wit=
h
>acetic acid (>99.8%)
>B: 80% acetonitrile in water
>
>INITIAL: 100% A
>LINEAR GRADIENT to: 50/50 A/B
>RINSE: 100% B
>END: 100%A
>We have tried many things to locate our problem. We changed the buffers,
>the columns but still there is a clear peak ones the gradient is started.
>It seems that this is a component that is present in the buffer A becaus=
e
>the peak increases with the volume of buffer A that was pumped over the
>column. Could the stability of the triethylamine be given problems and
>should we buy a new bottle since the present one is in use for some time
>now?
This is a classic problem.
Once one can determine that the ghost peak increases from increased
exposure to solvent, get rid of the source and start fresh. Also wash bo=
th
A & B solvent lines with 100% MeCN and clean both the reservoir bottles a=
nd
the solvent filters in those reservoirs (many times there is a thumb prin=
t
on them which contributes to the contamination problem). Less frequently=
,
it is the pumping system that is the source of the contamination.
Some use TFA in ampules to protect against this as a recurring problem, b=
ut
even so there are bad ampules of TFA. It is best and least expensive at
the start of this trouble shooting to buy a fresh bottle of reagent.
Thanks for sharing. We have all experienced this one, so you are in good
company.
Best regards,
Amos
Amos Heckendorf (nestgrp@world.std.com)
The Nest Group, Inc., Value Added Resellers of HPLC Columns (Vydac=81,
PolyLC=81, BioChrom Hydrocell=81, Jones Apex=81 & Genesis=81, Jordi-Gel=81=
,
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Bischoff Prontosil=81) and Isolute=81 SPE cartridges; ESA=81 PAGE gels; A=
mika
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8 or
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