Dear Carsten,

I measured up to 500 permil enriched PLFAs together with natural abundance
runs at the same run and no memory effects at all using a Finnigan Delta
Plus connected to a Trace GC 2000 and a combustion III interface.

Kind regards

Bruno

P.S.: Are you sure that linearity of the IRMS is given for up to 2000
permil?

********************************************
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:    Carsten Schubert [SMTP:[log in to unmask]]
Gesendet am:    Montag, 2. Dezember 2002 18:43
An:     [log in to unmask]
Betreff:        [ISOGEOCHEM] 13C GC-C-IRMS natural/enriched

Dear all,

we have a Finnigan Delta Plus hooked up to a GC combustion unit. In general
we are measuring lipids (fatty acids, sterols etc.) at natural abundance
levels. Newer research questions would make it necessary to label these
compounds in experiments with an enrichment of up to 2000 per mil. Now I am
afraid of getting memory effects after switching back to normal abundance
levels. Are there any ideas whether there are such memory effects and if
yes, to get around them. I would really appreciate any comments on this.

Regards, Carsten

__________________________________________________________________

Carsten J. Schubert
EAWAG
Limnological Research Center
CH-6047 Kastanienbaum, Switzerland
Phone: +41-41-349 21 95 Fax: +41-41-349 21 68
e-mail: [log in to unmask]

http://www.internal.eawag.ch/~schubeca/

http://www.eawag.ch/