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