Stable Isotope Geochemistry


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Gilles St-Jean <[log in to unmask]>
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Stable Isotope Geochemistry <[log in to unmask]>
Tue, 17 Feb 2004 09:54:52 -0500
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Hello Jean-Pierre
Depending on where you live and the rules regarding noxious gases in your region, institution etc.; I usually recommend having a dual-inlet for reference injection.  This applies for H2, CO, SO2 and other nasty gases.  The cost of CO alarms (not the home ones) can go as high as half the cost of a dual-inlet.  For example a group in Montréal, Québec, Canada would have had to disburse up to $25,000 for their alarm system due to srtict rules regarding CO in there institution. The industrial alarm has to alarm in the room, the corridor, central protection and minimise false alarms to the building. They went with a dual-inlet and have not regretted the purchase since.  The dual-inlet is not that difficult to retro-fit if needed.

The advantages of a dual-inlet are:
- Use lecture bottles  for reference gases that can last for up to 5 years (depending on use).  With these small lecture bottles you don't need the alarm system since the amount is not enough to cause problems.
- You can get calibrated reference gases (e.g. Ostech tanks) and/or natural abundance gases at a resonable price including CO2.
- The dual-inlet allows you to run ALL the Finnigan self diagnostic tests including sensitivity (ions/molecules) etc. available even in the old Isodat software.
- For special high precision samples you have a dual-inlet to use and can easily add a micro-volume if needed.

When I was in Italy a couple of years ago, the group there were running CO through an Isoprime without dual-inlet and the cost, I was told, was over $1000US per month for the reference tank.  CO at natural abundance levels is not cheap.  The cost of the tanks in this case would justify a dual-inlet on their instrument.
PS I don't know the price for a dual-inlet on the Micromass systems.  In 1990-92 it was about $38,000US, we bought 2 micro-inlets to upgrade our older instruments back then and I installed them myself (no installation fees), so 10 years later....??


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]

> -----Message d'origine-----
> De : Stable Isotope Geochemistry [mailto:[log in to unmask]]De la
> part de Girard Jean-Pierre
> Envoyé : 17 février 2004 02:50
> À : [log in to unmask]
> Objet : [ISOGEOCHEM] CO gas for CF-IRMS
> Dear list members,
> We are in the process of setting up a CF-IRMS system (Delta +
> XP, gas bench,
> TC-EA and flash EA) in our laboratory. We are somewhat
> uncertain as to the
> best design for the CO gas suppyling system, in terms of
> efficiency and
> security.
> If you have gone through this as well, we would like to hear
> about your
> choices in terms of storage of CO tank (inside, outside, security
> locker....), as well as tubing, vannes and purging system for the gas
> delivery line. We presently have a quotation from a major gas
> supplier which
> is outrageously expensive and we are looking for less costy, but fully
> secure, alternatives.
> Please, reply directly to me at [log in to unmask]
> Jean-Pierre Girard
> Isotope Geochemistry Unit
> 3 avenue C. Guillemin - BP 6009
> 45060 Orléans cedex 2 - France
> Tél. : - Fax :
> e-mail : [log in to unmask] - web : <>
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