Date of Award

Fall 2005

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Robert F. Dias

Committee Member

Elizabeth C. Minor

Committee Member

Kenneth G. Brown

Call Number for Print

Special Collections LD4331.C45 H49 2005

Abstract

The incorporation of sulfur into sedimentary organic matter is an important aspect of organic carbon preservation. A better understanding of the sulfur cycle and the formation of organo-sulfur compounds are necessary if we are to better understand the interaction of biogeochemical cycles of C, N, O, H. and S. Currently, the determination of 34S/32S in organic matter is limited to bulk organic samples. The sulfur isotopic analysis of individual organo-sulfur compounds within the sediments should allow for a more complete understanding of the sulfur cycle and the processes which lead to sulfur incorporation into organic matter. This interpretative development could elevate the analysis of sulfur in biogeochemistry to the level of sophistication that currently exists for C,H,and N.

To that end, a new GC-IRMS reductive pyrolysis reactor interface was developed for the σ34S determination of low-molecular weight organo-sulfur compounds. Modification to the existing GC-combustion-IRMS instrument consisted of changing the reactor catalyst, nickel-platinum wire, to platinum wire only, in1roducing a reductive gas (H2) instead of O2 for combustion, and adapting the temperature to either 600°C or

1000°C, depending on the compound being analyzed. The organo-sulfur compound is reductively pyrolyzed to H2S and subsequently analyzed by the IRMS (m/z = 36/34). The new pyrolytic method was evaluated using a suite of model compounds covering a range of chemical structure and C-S bond types. This new analytical technique shows great promise and with refinement, should provide the next analytical step towards a more in depth understanding of the biogeochemical cycling of sulfur.

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DOI

10.25777/cttz-a168

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