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HI Wolfram and Paul--

thanks guys...

take care

gerry

p.s. sometimes grannies do have to be taught how to suck eggs...

Dr W Meier-Augenstein wrote:

>Dear Gerard,
>
>
>At the risk of teaching my granny how to suck eggs, you are aware, aren't
>you that PoraPLOT columns are exquisitely sensitive to sharp increases in
>carrier gas pressure and any other kind of mechanical shock?
>
>When installing a PoraPLOT column, carrier gas pressure should be increased
>in 1 psi increments with 2 min intervals, as otherwise one risks the column
>bed to collapse / compact (leading to an increase in back pressure and poor
>chromatography).
>
>I'm afraid from what you describe it sounds like this happened to your
>column.
>
>Allegedly, the new PoraBOND columns do not suffer from this ailment and can
>even be used with pressure programmes (manufacturer's claim, not mine).
>
>Chrompack/Varian do as yet not offer PoraBOND equivalents for all the
>PoraPLOT columns but as luck would have it, they do a PoraBOND Q.
>
>>From experience, I would stick with Chrompack/Varian when it comes to PLOT
>columns.
>
>
>Cheers,
>
>Wolfram
>
>
>
>
>
>
>
>
>>-----Original Message-----
>>From: Stable Isotope Geochemistry
>>[mailto:[log in to unmask]] On Behalf Of Gerard Olack
>>Sent: 22 June 2005 04:58
>>To: [log in to unmask]
>>Subject: GasBench Plot column clogging
>>
>>
>>Hi All--
>>
>>We're having problems with the PoraPlot-Q capillary column
>>(0.32) that came with our GasBench.  We've been able to run
>>with the He pressure ~18 to 20 psi and have ~2+ mL/min flow
>>rates.  After swapping it out for a molesieve column, it's
>>back in and now requires 25 psi for ~1 mL/min flow rates
>>checked at end of column.  I've check connections, clipped
>>column ends, baked it out--but to no avail so far.  No
>>evidence for water/phosphoric acid on column (had that happen
>>before, clipped off brown section of column).  Would other
>>Q-Plot columns work better, e.g. Supelco (they claim to fuse
>>polymer to the silica column)?
>>
>>thanks...
>>
>>gerry
>>
>>www.geology.yale.edu/escsis/ESCSIS-web1.html
>>
>>
>>
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