Analysis of Carbon and Sulfur

National Geochemical Survey

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C, S

Analysis of Forms-of-Carbon and Sulfur (USGS laboratories)

Methods

Total Carbon. Total carbon is determined using an automated carbon analyzer. Approximately 0.20 g of powdered sample is combusted in an oxygen atmosphere at 1350°C to oxidize carbon to carbon dioxide. Moisture and dust are removed and the carbon dioxide gas is measured by a solid state infrared detector. For details, see Brown and Curry (2002a) and Jackson and others (1987).
Carbon present in carbonates. Carbonate carbon is determined as carbon dioxide by coulometric titration. The sample is treated with hot 2 N perchloric acid and the evolved CO₂ is passed into a cell containing a solution of monoethanolamine. The CO₂, quantitatively absorbed by the monoethanolamine, is coulometrically titrated using platinum and silver/potassium iodide electrodes. For details, see Brown and others (2002b) and Jackson and others (1987).
Organic Carbon. The amount of carbon present in organic compounds is reported as the difference between total carbon and carbonate carbon, both measured as described above.

Total Sulfur. Total sulfur is determined using an automated sulfur analyzer. ~0.25 g of sample is weighed and mixed with 1 g vanadium pentoxide flux. The sample is combusted in an oxygen atmosphere at 1350°C where the sulfur oxidizes to sulfur dioxide. Moisture and dust are removed and the sulfur dioxide gas is measured by a solid state infrared detector. For details, see Brown and Curry (2002b) and Jackson and others (1987).

Data analysis

		Distribution maps
Element	QA/QC	Conter- minous	Alaska	Hawai`i
C_tot (wt%)	In progress		no data	no data
C_org (wt%)	In progress		no data	no data
C_CO3 (wt%)	In progress		no data	no data
S_tot (wt%)	In progress		no data	no data

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U.S. Department of the Interior, U.S. Geological Survey
This page is part of U.S. Geological Survey Open-File Report 2004-1001
URL: http://www-tin.er.usgs.gov/geochem/doc/carbon-sulfur.htm
Maintained by Jeff Grossman
Last modified: 15:03:11 Tue 06 Jan 2004
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