Dear Greg and others,

Several years ago I constructed a GC-column based off-line vacuum line with
which I have analyzed trace (1-5%) carbonate in sulfide matrices (massive
sulfide ore from the Sullivan mine).    This allowed determination of d18O
and d13C to 0.1 ? on sometimes just a few micromoles of CO2.  The line uses
a 10 ft/0.25 in outer diameter HAYESEP-C column, home-built oven (120 oC),
plus a very-high efficiency trap I designed to capture the CO2 peak from the
He stream.  A full description of the line will appear next year in a
special issue of Chemical Geology.  Results of carbonate isotope
stratigraphy through the Sullivan deposit are published in a Geol. Assoc. of
Canada volume on the Sullivan deposit (available shortly). The line I built
uses manual valves, but the product gases from the phosphoric acid reaction
could, in principle, be separated with a gas-bench type device.  I chose an
off-line procedure because I was separating trace amounts of CO2 from large
samples.  The advantages is quantitative separation without isotopic
fractionation.

regards,
Bruce

Bruce E. Taylor, Ph.D.
Research Scientist
Geological Survey of Canada
601 Booth Street
Ottawa, Ontario  K1A 0E8
CANADA

PH:  613-995-4673 (office)
                 992-4046 (lab)
FAX: 613-943-1286
e-mail: [log in to unmask]

Personal URL:
http://www.nrcan.gc.ca/gsc/mrd/bio/taylor_e.html

LSI Lab URL: http://www.nrcan.gc.ca/gsc/mrd/mdag/lsilab/index_e.html


> ----------
> From:         Greg B. Arehart
> Reply To:     Stable Isotope Geochemistry
> Sent:         Tuesday, November 28, 2000 17:24
> To:   [log in to unmask]
> Subject:      Carbonates and sulfides
>
> Dear listmembers,
>
> As long as the subject of contaminants in carbonates has arisen, I would
> like to know what folks are
> doing these days about sulfides in carbonate samples.  I know that there
> are a number of methods for
> removing sulfides off-line, but has anybody dealt with significant sulfide
> contamination (percent
> level) in automated devices, particularly at elevated (>30C) temperatures
> of reaction?
> --
> Dr. Greg B. Arehart
> Department of Geological Sciences, MS-172
> University of Nevada, Reno
> Reno, NV 89557-0138
> *****please note new area code*****
> phone: 775-784-6470
> fax: 775-784-1833
> email: [log in to unmask]
>