Dear Sergey,

We used to do this conversion, and we had very good results  even with 1
micromole O2 - to 30 micromoles using the same converter.  The paper where
you can  find the description of this method  along with the first
description of a new technique measuring unconverted O2 by continuous flow
isotope ration mass spectrometer is K.Revesz, J.K. Bohlke, R.L.Smith,
T.Yoshinari , 1999 Stable Isotope Composition of Dissolved O2 Undergoing
Respiration in a Ground Water Contamination Gradient:  Morganwalp, and
Buxton eds. U.S.Geological Survey Toxic Substances Hydrology Program -
Proceeding of the Technical Meeting, Charleston, South Carolina, March
8-12, 1999,-- Volume 3--  Subsurface Contamination From Point Sources:
U.S.Geological Survey, Water-Resources Investigation Report 99-4018C, p.
323-328.  And an other one by the same authors IAEA International Symposium
on Isotope Techniques in Water Resources Development and Management ,
Vienna, 10-14 May 1999.
As I remember, the "secrets" are 1. do not go higher temperature than
500-560 C, (if you do your thermodynamic calculation you would see, that
higher temperature promote CO production), 2. continuously remove the CO2
from the reaction chamber by LN2 to avoid its decomposition to CO on the
hot surface and to promote the complete reaction.    3. Activate the
charcoal before using it by heating it up to the reaction temperature for a
minute under vacuum.

Good luck:

Kinga



Kinga Revesz
Chemist, Stable Isotope Laboratory
U.S.Geological Survey
MS 431
Reston, VA 20192
T:703-648-5865
FAX: 703-648-5274



                    Sergey Assonov
                    <assonov@mpch-mai        To:     [log in to unmask]
                    nz.mpg.de>               cc:
                    Sent by: Stable          Subject:     how to convert O2 into CO2
                    Isotope
                    Geochemistry
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                    01/22/01 03:24 PM
                    Please respond to
                    assonov





Dear all,

how to convert O2 into CO2, avoiding CO production? Amount of O2 is about
20
mmol.
that seems to be simple question and many works are published, but I like
to
find out a simplest way.
References and advises are really welcome.

Thanks,

Sergey

----------------------------------------
Dr. S.Assonov,
Abtailung fuer Luftchemie,
Max-Planck Intitut fuer Chemie,
J.J.Becher Weg 27,
55128 Mainz, Germany

Phone : +49-6131-305-463
Fax   : +49-6131-305-436