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Subject:
From:
Dr W Meier-Augenstein <[log in to unmask]>
Reply To:
Date:
Mon, 23 Feb 2004 08:17:29 -0000
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Dear Bruno and others interested in using PLOT columns,


Traditional PoraPLOT columns are sensitive to abrupt increases in
carrier gas pressure. The reason for this is the nature of the column.
PLOT stands for Porous Layer Open Tubular (column) as this type of
column is not wet coated (WCOT) to produce a film but "packed" with a
porous polymer material similar to an old fashioned packed column filled
with e.g. HayeSep Q or Porapak S.

Consequently, any sudden increase of pressure can (1) compact the porous
polymer particles and thus the phase bed (= loss of chromatography) and
(2) lead to discharge of stationary phase through the end of the column
(hence the particle trap). So, when installing a PoraPLOT column,
carrier gas pressure should be increased slowly by, say, 1-2 psi per
minute. This also means there is a maximum pressure a PoraPLOT column
can withstand but I couldn't tell you what this figure is off hand.

Chrompack (now Varian) have started to phase out PoraPLOT columns,
however, and to replace them with PoraBOND columns, where as the name
suggest the porous stationary phase is now bonded thus making it more
resilient to pressure pulses (and water injections) while also reducing
column bleed, allegedly.

Standard columns, i.e. coated with a liquid film of stationary phase, do
not exhibit this kind of pressure sensitivity but, of course, there is a
physical limit to the column head pressure any column will take. As nice
as EPC is, one should always consider to what pressure a desired flow
rate of e.g. 1.5 ml/min equates when operating at higher temperatures.


Cheers,

Wolfram




> -----Original Message-----
> From: Stable Isotope Geochemistry
> [mailto:[log in to unmask]] On Behalf Of Dr. Bruno Glaser
> Sent: 21 February 2004 22:03
> To: [log in to unmask]
> Subject: AW: [ISOGEOCHEM] Isodat 2.0
>
>
> Dear Gilles,
>
> please could you explain in more detail the problems
> encountered with PLOT columns when rapidly increasing
> pressure from EPC. Could this also be the case with other
> types of columns?
>
> Thanks a lot
>
> Bruno
>
> Dr. Bruno Glaser
> Institute of Soil Science and Soil Geography
> University of Bayreuth
> D-95440 Bayreuth
> Germany
> Email: [log in to unmask]
> Phone: ++49-921-552254
> Fax: ++49-921-552246
> Web: http://www.geo.uni-bayreuth.de/bodenkunde
>
> -----Ursprüngliche Nachricht-----
> Von: Stable Isotope Geochemistry
> [mailto:[log in to unmask]]Im Auftrag von Gilles St-Jean
> Gesendet: Donnerstag, 19. Februar 2004 22:51
> An: [log in to unmask]
> Betreff: Re: [ISOGEOCHEM] Isodat 2.0
>
> Hi all
> It seems that Isodat 2.0 will run happily on Windows XP (with
> all the latest
> patches) with the older GPIB cards (both the ISA and the
> PCI).  I have also run the GPIB using a USB port with
> National Instruments' GPIB-USB-B with success from a laptop
> as well as the normal computer running the IRMS. There seems
> to be 2 obvious glitches with the software where one of which
> has already received a fix and those are:
> 1) The amplifier zero (measure) routine crashes.  A faulty
> .dll has been repaired and this bug is now gone and will be
> part of a post 1.35 service pack.
> 2) The Peak Center Offset routine hangs.  99.9999% of the
> users don't need this remnant of Isodat old. To be fixed later.
>
> The driver for the ISA runs right out of the Isodat 2.0
> install and the PCI driver for XP from NI is available on
> their website.
>
> We have run close to 500 samples of EA (N2, CO2 and SO2) and
> TOC-Analyser in the last two weeks without a glitch (ISA GPIB
> card).  Reference injection from both the bellows and the
> ConFlo II-III run without a hitch either.  I think it is safe
> to say that you can go to Isodat 2.0 and run your samples.
> There is a bit more of a learning curve with this version
> since you can now save GC (HP and THERMO-TRACEGC) methods
> (injector temperarures, flow etc..) as well as autosampler
> methods (yes with obvious names as a file).  You can mix and
> match any of these to an IRMS method.  Really nice stuff, no
> more front panel buttons to program. Also you don't need the
> game port anymore (see a previous posting from me about
> this).  If you don't have enough COM ports on the computer
> use a USB-COM port adapter to add as many as you need.
>
> PS Beware of this, ease of use, if you use PLOT columns.
> Rapid changes in pressure from EPC can destroy a $1200 PLOT
> column, read the warning sheet with the PLOT column for more info.
>
> Gilles
>
> Gilles St-Jean
> U. d'Ottawa / U. of Ottawa
> Sciences de la Terre / Earth Sciences
> Laboratoires d'isotopes- G.G.Hatch -Isotope Laboratories
> 140 Louis Pasteur, Ottawa, Ontario, Canada
> K1N 6N5
> Tel: 1-613-562-5800 xt 6830 (Bureau / Office)
>                     xt 6839 (Bureau 2/ Office 2)
>                     xt 6836 (Lab)
> Fax: 1-613-562-5192
> Courriel / e-mail: [log in to unmask]
> Web: www.isotopes.science.uottawa.ca
> -----Message d'origine-----
> De : Stable Isotope Geochemistry
> [mailto:[log in to unmask]]De la part de David A.
> Mucciarone Envoyé : 20 janvier 2004 14:09 Ŕ :
> [log in to unmask] Objet : Re: [ISOGEOCHEM] Isodat 2.0
>
>
> I recently had a conversation with Frank Trensch about
> upgrading a Delta plus to run the latest version of ISODAT
> under Win-XP. This is my understanding. If you want an
> optical interface you need to purchase a new Delta
> XP/353/etc. Those of us with Delta plus IRMS are stuck with
> NT until National Instruments provides either Windows 2000 or
> Windows XP drivers for either the ISA (probably unlikely) or
> the PCI interface cards (more likely). Frank mentioned that
> if this happens then there should be no/minimal/solvable
> problem running a newer version of Windows on the older Delta
> plus instruments.
>
> To date folks have been able to run/use Win 2000 with the
> ISODAT-NT version but not controlling the instrument well or
> at all. They have been using it mostly to post-process data
> under Win-2000.
>
> So we may be stuck for a while using Win-NT and ISODAT-NT
> until either someone out there works it out or until National
> Instruments provides a new driver. Something some of us have
> come to terms with on Finnigan instruments. Some of us have
> gone from Concurrent DOS to Real32 to Win-NT and perhaps XP
> running a multitude of ISODAT versions. For sometime I
> thought I would be stuck running Real32 so personally the
> Win-NT version is welcomed with the hope that I have it less
> than Real32.
>
> Dave
>
> At 05:52 PM 1/17/2004 -0500, you wrote:
>
> I am considering this, as I don't care to be stuck with NT
> for the life of my instrument, which is currently only 3
> years old. Has anyone tried it? What exactly does 'not
> stable' mean? A glitch every run or every 100 runs? Every 100
> would put it on par with NT ver 1.2 in my experience, and I
> lived with for almost a year.
>
> Is there any way of upgrading a Delta Plus to the optical
> interface? I know the bulk of the electronics and controls
> are different between a Plus and a XP and I don't want all
> that (well, I do, but I know that's not possible), but It
> would be nice to have a simple optical interface for my Plus
> that does what my GPIB does now.
>
> I spoke to Frank Trensch on this matter also and I asked the
> very same question. He said the only way to get the optical
> interface is to purchase a Delta XP. It seems the electronics
> are completely different in the two and an upgrade is not possible.
> ***********************************************************
> David A. Mucciarone
> Stanford University
> Dept. of Geological & Environmental Sciences
> Building 320, Room 118
> Stanford, CA 94305-2115
> 650-723-0817 (O) 650-725-2199 (F)
> http://pangea.stanford.edu/isotope/dam/sil_hom> e.html
>
> ***********************************************************
>

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