Hi Fred,

Instead of use-once-only glass ampoules you could use small reaction vessels connected to a vacuum manifold.

You would add CuO to the reaction vessel/s first, hook them up to the manifold, and then open the valves to evacuate the vessel/s.  Close valve/s once the vessel/s is/are evacuated.  This done you could fill vessel/s (still connected to the manifold) individually (selectively opening a valve at a time) with gas by letting the gas get drawn into a vessel.  You could even consider cooling evacuated vessels with a Dewar filled with liquid N2.

Once filled and the valve is closed, combust the sample by heating the vessel.  You can then cool the vessel to e.g. -20°C (NaCl, ice, water slush) to trap water on the walls of the vessel, followed by "moving" the CO2 via the manifold into another (pre-evacuated) vessel that subsequently can be attached to your Dual Inlet.

The above should also work with glass ampoules provided you can find a way to attach the neck of an ampoule to a vacuum manifold by way of a self-built or purchased adapter.  Arndt Schimmelmann is probably the best person to ask for advice given his vast experience in off-line sample preparation for Dual Inlet work.

Best,

Wolfram


From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Fred Martin Kaaby
Sent: 03 November 2016 08:48
To: [log in to unmask]
Subject: [ISOGEOCHEM] Off-line preparation method for d13C of methane

Dear Isogeochem

I am looking for a good and simple offline preparation technique to combust pure methane for d13C determination on dual inlet.

Previously I have added my solid or liquid sample to CuO and evacuated it in a sealed glassampulle. Then combusted it into a furnace oven, before drying the CO2 before using the dual inlet.

I guess there is something similar for gases too. But how do I introduce my gas to the ampulle? I hope I don't need to reinvent the wheel.


Hilsen/Regards
Fred Martin Kaaby





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