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
I'm afraid from what you describe it sounds like this happened to your
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
> -----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)?