Dear List members,

most recently, we are observing an instability of our Delta plus IRMS
coupled with a Trace GC 2000 and a combustion interface III. If we run
standard on/off with a constant CO2 amount we get pretty constant d13C
values. However, if we try to vary the CO2 pressure there is a drift of
up to 2 delta per mil. If we switch over to EA-IRMS, the drift
disappears.

What is a bit strange are increasing delta vs SMOV 18/16 values with
time injecting the same samples although the 45/44 and the d17O corr
d13/12 ratios remained more or less constant over time.

Any suggestions are highly appreciated.

Kind regards

Bruno

Dr. Bruno Glaser
Insitute of Soil Science and Soil Geography
University of Bayreuth
D-95440 Bayreuth
Germany