>Dear listmember
>
>I was asked to determine carbonate content in a solid powder and did the
>following with my VG Optima GC-IRMS normally in use for simple breath
>analysis.
>Is this a good method?
>Improvements suggested?
>
>*       100mg solid powder put in 1.8 ml gas tight glass vials
>*       Vials flushed with pure helium in a glove chamber to reduce
>background CO2
>*       200 ul 0.1M phosphouric acid (>10x molar excess) added with a
>syringe via the septa
>*       mix 5 min wait 30 minutes
>*       Headspace gc-irms to get total CO2 and isotope ratios as a bonus
>
>Got nice results anyway, but have to be sure I did not do any major
>methodology or practical mistakes
>
>Thanks!
>
>By the way - would it be possible to tell what carbonate was in the material
>from the delta values?
>Got -3.4 for my unknown samples and -8.0 from my Na2CO3 standard. Does it
>tell me anything else then that it was not laboratory air CO2 in my samples?
>
>Best wishes,
>Lars

Lars and others,

I reviewed a paper on this subject for Chemical Geology several years ago
and I bielieve it was published.  One of the authors was Kristnamurty.

Hal


Dr. Haraldur R. Karlsson
Associate Professor of Geosciences
Department of Geosciences, and
Department of Chemistry and Biochemistry (joint)
Texas Tech University
Box 41053
Lubbock, TX 79409, USA

(806)-742-3130 office
(806)-742-3112 lab
(806)-742-0100 Dept. fax