Reinhard,

The technique with Cd works fine here. We normally use the
technique on a NO3- solution with 100mg N/L (and 0.3663 - 10
atom% 15N). We use flat bottles of 180 mL. The remaining part of
the bottle (130mL) has a N2O-concentration of about 5200 ppm.
We haven't tried making larger amounts of N2O, but i think the best
way would be to make different batches of N2O and then mix the
resulting N2O somehow.
We should test it further, but it seems that the yield of the N2O
production lowers with higher concentration of NO3- in the starting
solution.

You should also know that we evacuate the bottles right after the
Cd is added, and that we fill the bottle with He-gas after 2 hours of
reaction (this could also be done with N2). This way we can be
sure that there is no influence of air or other compounds.

Our problem though with this technique is that Cd is very expensive
(and dangerous), and that it is much work.

Peter.


On 24 May 2000, at 13:07, Dr. Reinhard Well wrote:

> Peter,
> we are also seeking a convenient source of 15N labelled N2O.
> Therefore I sent a request to the ISOGEOCHEM mailing list a few
> weeks ago (see below). Promochem (Box 100955, D-46469 Wesel,
> Germany, +4928198870; www.promochmem.com) offers 98 atom%
> N2O in 0.1 bottles for DM 985,- or 0.46 L steel bottles for DM
> 1135,. How is your experience with the Cd-reduction technique? Is it
> suitable for producing larger quantities, i.e. approx. 1 L of N2O? Our
> purpose is to use the 15N2O in reduction experiments with soils.
> Therefore we would not need pure N2O.
>
> Reinhard
>
> Old message from 20 Apriol 00:
> Dear Listmembers,
>
> we are planning to conduct soil incubation experiments with 15N
> labeled N2O. Can anyone recommend a simple and inexpensive
> procedure to produce a few liters of a gas mixture with highly
> enriched N2O (at least 10 ppm) in unlabeled N2? We were
> considering to use the following procedures:
> -Reduction of 15N labled NO3- to NO2- using Cu coated Cd foil and
> reduction of NO2- to N2O by adding NH2OH (Stevens & Laughlin 1994,
> Soil Sci. Soc. Am. J. 58:1108-116). -Anaerobic incubation of soils
> amended with 15N-NO3 and C2H2 to produce N2O from denitrification
> (Lensi et al., 1985, Soil _Biol. Biochem. 17, 733-734) with subsequent
> trapping of C2H2 in alkaline KMnO4 (Malone et al., 1998, Soil Biol.
> Biochem 30, 31 - 37). Has anyone used these or other procedures to
> produce larger quantities of 15N2O? Thanks in advance.
>
>
> On 24 May 00, at 12:10, Peter Vervloedt wrote:
>
> > Hi,
> >
> > Can anyone tell me if it's possible to purchase N2O-reference gas
> > with various 15N abundances? For the moment we use N2O that is made
> > by chemical tranfsormation from NO3-. The procedure to transform
> > NO3- in N2O is time-absorbing and it involves the use of Cadmium.
> >
> > Is there another way to acquire N2O reference gas?
> >
> > Thank you very much.
> > -----------------------------------------
> > Peter Vervloedt
> > Ghent University
> > Laboratory of Applied Physical Chemistry
> > Coupure Links, 653
> > 9000 Gent
> > tel.: +32 9 264 60 00
> > fax.: +32 9 264 62 30
> > e-mail: [log in to unmask]
> > ----------------------------------------
> >
>


-----------------------------------------
Peter Vervloedt
Ghent University
Laboratory of Applied Physical Chemistry
Coupure Links, 653
9000 Gent
tel.: +32 9 264 60 00
fax.: +32 9 264 62 30
e-mail: [log in to unmask]
----------------------------------------