Hi:



Recently, we did some work to understand the salt effect on the CO2-H2O
isotopic exchange equilibrium. It will be published in the Proceedings of
"Symposium on Quality Assurance for Analytical Methods in Isotope Hydrology"
, IAEA, Vienna. The equilibrium also depends on other parameters, such as
alkalinity, buffering capacity, pH, and amount of total dissolved CO2, etc.,
which are still to be studied. If anyone is interested, I can send a copy.



It looks with the discussion that one can reduce the analysis time with
equilibrating CO2-H2O at higher temperature (say 40ºC). If it is really the
objective, the answer is NO.  There will be other problems like water vapor.
There will be substantial amount water vapor that will affect the oxygen
isotopic analysis even one condenses the water vapor before injecting the
CO2 into the mass spectrometer. CO2 is highly soluble in water. So, the
condensed vapor will have some CO2 that will affect the isotopic composition
of the equilibrated CO2. Although such experiments must always be
encouraged, one gets sometimes valuable information with doing work against
the normal procedures.



I hope it should be of some contribution to the discussion.



Cheers



Mahendra