Matheus -

I have seen what you describe done with CO2 concentrations in air samples,
and do not see a reason why in theory at least, it would not work for a
modified gas evolution technique for DIC (assuming all DIC is consistently
evolved).  See Leuenberger et al (2000) CO2 concentration measurements on
air samples by mass spectrometry.  Rapid Comm, in Mass Spec 14:1552-1557:
They obtained precision of 3ppmv for small air samples with both a MAT 250
and Delta Plus XL.

I would also build on what Ian Cartwright mentioned, Garrels and Christ or
Stumm and Morgan provide carbonate equilibria reactions that can be used to
calculate DIC accurately based on water temperature, [CO2], and pH.

Cheers,

Noah
___________________________
Noah J Karberg, Ecologist
USDA Forest Service
Northern Research Station
410 MacInnes Drive
Houghton, MI 49931
(906) 482-6303 ext 21


                                                                           
             Matheus Carvalho                                              
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Hello everybody, I am going to make a question that I
know it has the risk of being very stupid. Is it
possible to quantify (or at least estimate) the amount
of DIC in a water sample, analyzed using a Gas Bench
and Delta XP, using the chromatogram generated by
Isodat as a basis (of course, a standard with known
DIC concentrationi would be measured too, and
precautions to use a precise sample volume, etc)?
I am making this question because when running a few
samples, the difference between the peak height of
some samples was very marked, which to me suggests the
possibility of quantification.

Thank you for any help,

Matheus Carvalho

PhD Student
Kitasato University School of Fisheries Sciences

Matheus C. Carvalho
PhD student
Kitasato University - School of Fishery Sciences
Japan

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