I assume this is an easy question but it seems my last math class was a 
long time ago.
Usually I don't care about the exact value of my CO2 ref gas on our 
gasbench system since everything is normalizied to reference materials 
with known values (and working gas cancels out). I just type in a value 
for the working gas in the isodat standard editor which will give a 
delta value close to the correct value.

I need to calculate the CO2 value of the working gas now and my idea was 
just to caluclate the things backwards. Assuming that my reference 
material (e.g. NBS19) will produce a CO2 with a known value it should be 
possible the calculate the delta value of the working gas etiher from 
the raw delta values or the ratios given in Isodat by treating the ref 
gas as the sample and the NBS 19 as the standard gas. However, sitting 
in front of Isodat and the equations it is not so obvious anymore...can 
anyone point me in the right direction?


Dr. Robert van Geldern
GeoZentrum Nordbayern / Applied Geosciences
University of Erlangen-Nuremberg
Schlossgarten 5
91054 Erlangen, Germany

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