Why don't you just define a method that uses the left volume as standard
(with NBS19)  and the right volume as sample (with WS) ? If you enter
NBS19 in the standard editor, the delta of the working standard will be
reported vs. PDB directly without any need to calculate.



Manfred Jaklitsch 
International Atomic Energy Agency 
Department of Nuclear Sciences and Applications 
Isotope Hydrology Laboratory 
P.O. Box 100 
A-1400 Vienna, Austria 

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-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On
Behalf Of [log in to unmask]
Sent: Friday, 09 July 2010 08:38
To: [log in to unmask]
Subject: Calculating the delta of the working gas

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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