Thanks for the advice, Gerald. 
We may ultimately stick with the Poraplot Q rather than the Porabond, as I 
have been told that the PoraPlot gives better separation of N2O and CO2, 
which is an issue in some of our samples from anaethetised patients. If 
anyone else could comment on this, and even send some chromatograms/ 
temperature/flow rates, I'd be very grateful as even on a PoraPlot colum, 
N2O can be a problem (especially as sometimes N2O is used in 
anaesthesia at up to 50% so gives a huge mass 44 peak close to CO2).

Incidentally, Thermo Bremen do not have experience yet with a PoraPlot in 
the GasBench.

As a related question, does anyone out there separate CO from N2 on a 
Gasbench with a Plot column, and if so, how?

Simon




Date sent:      	Mon, 4 Dec 2006 10:27:16 -0500
From:           	Gerard Olack <[log in to unmask]>
Subject:        	Re: Gasbench GC Columns

HI Simon--

I had problems awhile back (last year, 6/22/05, Paul Eby and Wolfram 
Meier-Augenstein helped if you want to check the archives) with our Plot 
column and went with the PoraBond Q (Varian's replacement for the 
PoraPlot Q).  So far so good.  He flow has been constant at 10 psi and 
the peak shape has been good.  The He for the flushing line comes off 
the main He line too--and we're not getting the same flow through there 
as we were before when the He pressure was higher.  Everything else 
seems ok, so we just move the flushing line to it's own He tank.  The 
only other issue that came up since then was some broad peaks coming 
through during some water runs, unrelated to the current runs CO2 
pulses.  That seemed to be sample type specific (water from trees), and 
may have been due to some organic contaminants coming through or 
perhaps 
water was making it past the drying tubes--and showing up in a run 
further down the line when it finally made it through the GC.  The 
problem went away when we stopped running those samples--and next time 
we'll have to remember to treat them with carbon black.

take care

gerry

Simon Eaton wrote:
> We need a replacment PLOT column for our GasBench (CO2, H2). We 
> have used CP Poraplot Q 25m. Does anyone have any experience of the 
> PoraBond Q in the GasBench? It it supposed to be less easily damaged by 
> any pressure fluctuations.
>
> Simon
>
>   


-- 
Simon Eaton, 
Senior Lecturer in Paediatric Surgery and Metabolic Biochemistry
Unit of Paediatric Surgery
Institute of Child Health
30 Guilford Street
London WC1N 1EH
Phone + 44 (0)20 7905 2158 (Office, Answer)
      + 44 (0)20 7905 2396 (Laboratory)
Fax   + 44 (0)20 7404 6181
Mobile + 44 (0) 7762 180877