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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


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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]
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Simon Poulson
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Dept. of Geological Sciences & Engineering MS-172
University of Nevada - Reno
1664 N. Virginia St.
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(775) 784-1104
Fax: (775) 784-1833
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