On Monday, 18 Jan 1999, Manfred Schmitt wrote:
> Dear all,
> dones anyone have a good method for the analysis of 18O/16O ratio of absolute
> alcohol?
> Presently we use a pryolysis method at 800°C and analysis of mass 28 and 30 of
> the GC-seperated CO in a continuous flow isotope MS. However, we are not very
> happy with the reproducibility. Are there better preperation methods?
I would strongly suspect your 'pyrolysis' temperature; 800 C appears
to be a trifle too low. According the the Boudouard equilibrium, at
800 C there is still some CO2 around (10% CO2 vs 90% CO). To generate
CO exclusively, the reactor temperature has to be > 1050 C. Most of
the pyrolysis work published mentions 1100 C as the temperature of
choice.
The next thing to look at would be your pyrolysis reactor. Is it just
an empty ceramic tube or do you load it with a carbon source (e.g.
nickelized carbon or carbon fibres)?
Lastly, have a look at papers written by G.D. Farquhar (1997), I.
Begley & C. Scrimgeour (1996, 1997) and H.J. Tobias & J.T. Brenna
(1996, 1997).
Regards,
Wolfram
*****************************************************
Dr. W. Meier-Augenstein, CChem MRSC
Lecturer/Research Fellow
University of Dundee, Dept. of Anatomy & Physiology,
Small's Wynd, DUNDEE DD1 4HN, United Kingdom
Tel.: +44-(0)1382-34/5124, /4968
Fax: +44-(0)1382-34/5514
e-mail: [log in to unmask]
URL: http://www.dundee.ac.uk/anatphys/wma/wolfram.htm
*****************************************************
NB Message is confidential and for recipient only: Unauthorized reading and copying
may result in legal action! Opinions expressed those of author not institution.
LEGAL NOTICE: Unless expressly stated otherwise, this message is confidential and
may be privileged. It is intended for the addressee(s) only. Access to this
e-mail by anyone else is unauthorized. If you are not an addressee, any
disclosure or copying of the contents of this e-mail or any action taken (or not
taken) in reliance on it is unauthorized and may be unlawful. If you are not an
addressee, please inform the sender immediately.
|
