Re: use of Dräger tubes for separation of H2S
from CO2
Shaun,
I don't know anything about using Drager tubes, but I seem to
recall a study a while back (approx. 2000, maybe?) that ran into the
same problem that you have. They solved the problem by putting
some silver phosphate into a cold finger on a vacuum extraction line,
and then froze the gas sample into the cold finger and let the sample
react for a few minutes at room T, presumably to form silver sulfide
and phosphoric acid. I recall reviewing the paper, and making
sure that the authors included some additional details about this
technique to clean up their gas samples (it wasn't a methods
paper)
Unfortunately, I can't remember the authors, nor do I have a copy
of the paper that I can find - maybe another Isogeochemer (who's
younger and whose memory isn't shot like mine apparently is) might
recall this paper?
Cheers,
Simon
Dear all,
We are trying to separate H2S from CO2
gas samples in a vacuum line, prior to isotopic analysis of carbonates
which are variably mixed with different proportions of different
sulfide minerals, particularly As-rich pyrite (which seems to dissolve
very readily in phosphoric acid).
I read with interest some of the
discussion from a few years ago on the Isogeochem list on this topic,
particularly with regard to the potential use of Dräger tubes
to remove H2S from CO2 samples.
Does anyone have practical experience
with fitting and using Dräger tubes in a vacuum line for this
purpose?
If so, could you tell me:
(a) what model of tube you used (Drager
manufactures about 8 different tubes for H2S detection)
(b) What the OD of the tubes are, in
order that we can try to rig something to fit the tubes to our
existing 1/4" and 1/2" Ultratorr fittings.
(c) What your "procedure" was
to allow the tubes to remove the H2S gas, i.e. did you trap water
before or after the Dräger tube, how long did you allow the gas
to interact with the Dräger tube prior to capture of the CO2
for subsequent analysis etc.
Are there any other practical methods or
techniques that people have used? Ideally, we are looking for a method
that can readily be used for hundreds of samples.
Cheers,
Shaun
---------------------------------------------------------
Shaun Barker
Post-doctoral Fellow
Mineral Deposit Research
Unit
Department of Earth and Ocean
Sciences
University of British
Columbia
Vancouver, BC
Canada V6T 1Z4
Tel: (+1) 604 822-1874
fax: (+1) 604 822-6088
email: [log in to unmask]
----------------------------------------------------------
--
*****
Simon Poulson
Research Professor
Dept. of Geological Sciences & Engineering MS-172
University of Nevada - Reno
1664 N. Virginia St.
Reno, NV 89557-0138. USA
(775) 784-1104
Fax: (775) 784-1833
[log in to unmask]
http://www.mines.unr.edu/isotope/simonhome.html
*****