The use of dithiothreitol for the quantitative analysis of elemental sulfur concentrations and isotopes in environmental samples

Martin R. Kurek, William P. Gilhooly, Gregory K. Druschel, Molly D. O'Beirne, Josef P. Werne

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Determining the concentration and isotopic composition of elemental sulfur in modern and ancient environments is essential to improved interpretation of the mechanisms and pathways of sulfur utilization in biogeochemical cycles. Elemental sulfur can be extracted from sediment or water samples and quantified by converting to hydrogen sulfide. Alternatively, elemental sulfur concentrations can themselves be analyzed using HPLC and other methodologies; however, the preparation and analysis times can be long and these methods are not amenable to stable isotopic analysis. Current reduction methods involve the use of costly and specialized glassware in addition to toxins such as chromium chloride or cyanide to reduce the sulfur to hydrogen sulfide. The novel reduction method presented here uses dithiothreitol (DTT) as a less toxic reducing agent to obtain both elemental sulfur concentrations and isotopic composition from the same sample. The sample is dissolved in an aqueous or organic liquid medium and upon reaction with DTT, the elemental sulfur is volatilized as hydrogen sulfide and collected in a sulfide trap using an inexpensive gas extraction apparatus. The evolved sulfide concentrations can easily be measured for concentration, by absorbance spectrophotometery or voltammetry techniques, and then analyzed for sulfur isotopic composition. The procedure is quantitative at >93% recovery to dissolved elemental sulfur with no observed sulfur isotope fractionation during reduction and recovery. Controlled experiments also demonstrate that DTT is not reactive to sulfate, sulfite, pyrite, or organic sulfur.

Original languageEnglish (US)
Pages (from-to)18-26
Number of pages9
JournalChemical Geology
Volume481
DOIs
StatePublished - Mar 20 2018

Bibliographical note

Funding Information:
We thank Jacob Burch (IUPUI) and Alyssa Henke (IUPUI) for their assistance with elemental sulfur and pyrite extractions. We would like to acknowledge the Integrated Nanosystems Development Institute (INDI) at IUPUI for use of their Bruker D8 Discover X-Ray Diffraction Instrument, which was awarded through a National Science Foundation grant [ MRI-1429241 ]. We appreciate those who provided samples for our experiments: Brenda Blacklock (IUPUI) provided cysteine, William Elliott (University of Southern Indiana) provided shale, Amy Myrbo (LacCore and Continental Scientific Drilling Coordination Office, University of Minnesota) provided lake sediment, and Philippe Schmitt-Kopplin (Helmholtz Zentrum München) provided dissolved organic matter. The manuscript benefited from helpful suggestions made by Alice Bosco-Santos (UNICAMP; IUPUI). We thank Editor-in-Chief Michael Böttcher and two anonymous reviewers for their thoughtful and helpful comments. This work was supported by a National Science Foundation grant [ EAR-1424228 ] to WPG and JPW. Appendix A

Publisher Copyright:
© 2018 Elsevier B.V.

Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.

Keywords

  • Cryptic cycles
  • Dithiothreitol
  • DTT
  • Elemental sulfur
  • Sulfur isotopes

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