Dear Roland,

measuring (bulk) d15N and d13C in the same sample is a standard procedure
coming with each type of EA-IRMS machine. I am not quite sure whether you
will find a detailed description in a scientific paper. As you certainly
know, the capability of measuring subsequently d15N and d13C successfully
in a bulk sample depends on several things:

1. Amounts of N and C in your sample: Normally, I measure only N and C
together in a dilution of 1:10 (Finnigan specific !!!) if the (in my case
soil) samples have a C:N ratio around 10. In this case both N and C signal
intensities are in the optimum working range. If not I would suggest to run
d15N and d13C separately.
2. Desired accuracy and precision. Normally, I adjust the sample weight for
optimum d13C analyses and just measure the d15N value along with it. In
most cases I get more or less usable d15N values as well. However, if I am
interested especially in d15N values, I run a separate set of samples just
for d15N values as you normally need much more sample weight to get a very
good precision.
3. Using appropriate calibration procedures. Normally, I use each three
certified !!! standards with different values both for d13C and d15N
measurements and it has been shown that the d values depend strongly on the
gas pressure.

Hope this helps.

Kind regards

Bruno

********************************************
Dr. Bruno Glaser
Institute of Soil Science and Soil Geography
University of Bayreuth
D-95440 Bayreuth
Germany
Phone: ++49-921-552254
Fax:     ++49-921-552246
Email: [log in to unmask]
Web:  http://www.geo.uni-bayreuth.de/bodenkunde
********************************************

-----Ursprüngliche Nachricht-----
Von:    Roland A. Werner [SMTP:[log in to unmask]]
Gesendet am:    Freitag, 22. November 2002 12:20
An:     [log in to unmask]
Betreff:        [ISOGEOCHEM] d13C and d15N from the same sample

Dear Isotope community,

I am interested in measuring d13C and d15N values from the same sample
(or d18O and d2H from the same sample). Can anyone provide me with
literature citations concerning methodological papers or applications of
this in any field.
Thanks a lot + Best regards

Roland