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Techniques and Methods 10–C4

Determination of the δ34S of Total Sulfur in Solids; RSIL Lab Code 1800

By Kinga Révész and Tyler B. Coplen

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The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1800 is to determine the δ(34S/32S), abbreviated as δ34S, of total sulfur in a solid sample. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total sulfur in a solid sample into SO2 gas. The EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines the relative difference in stable sulfur isotope-amount ratio (34S/32S) of the product SO2 gas. The combustion is quantitative; no isotopic fractionation is involved. Samples are placed in tin capsules and loaded into a Costech Zero-Blank Autosampler on the EA. Under computer control, samples are dropped into a heated reaction tube that combines both the oxidation and the reduction reactions. The combustion takes place in a helium atmosphere that contains an excess of oxygen gas at the oxidation zone at the top of the reaction tube. Combustion products are transported by a helium carrier through the reduction zone at the bottom of the reaction tube to remove excess oxygen and through a separate drying tube to remove any water. The gas-phase products, mainly CO2, N2, and SO2, are separated by a gas chromatograph (GC). The gas is then introduced into the isotope-ratio mass spectrometer (IRMS) through a Thermo-Finnigan ConFlo II interface, which also is used to inject SO2 reference gas and helium for sample dilution. The IRMS is a Thermo Delta V Plus CF-IRMS. It has a universal triple collector with two wide cups and a narrow cup in the middle. It is capable of measuring mass/charge (m/z) 64 and 66 simultaneously. The ion beams from SO2 are as follows: m/z 64 = SO2 = 32S16O16O; and m/z 66 = SO2 = 34S16O16O primarily.

Revised August 2, 2012 (version 1.2)

First posted 2006 and revised 2007

For additional information contact:
Director, Reston Stable Isotope Laboratory
U.S. Geological Survey
12201 Sunrise Valley Drive, MS 431
Reston, VA 20192

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Suggested citation:

Révész, Kinga, Qi, Haiping, and Coplen, T.B., 2012, Determination of the δ34S of total sulfur in solids; RSIL lab code 1800, chap. 4 of Stable isotope-ratio methods, sec. C of Révész, Kinga, and Coplen, T.B. eds., Methods of the Reston Stable Isotope Laboratory (slightly revised from version 1.1 released in 2007): U.S. Geological Survey Techniques and Methods, book 10, 31 p., available only at (Supersedes versions 1.0 and 1.1 released in 2006 and 2007, respectively.)



Summary of Procedure

Reporting Units and Operational Range

Reference Materials and Documentation

Labware, Instrumentation, and Reagents

Sample Collection, Preparation, Analysis, Retention Times, and Disposal

Data Acquisition, Processing, Evaluation, Quality Control, and Quality Assurance

Health, Safety, and Waste-Disposal Information

Revision History

References Cited

Appendix A. Step-by-Step Procedure to Log-In Samples to LIMS-LSI

Appendix B. Step-by-Step Procedure to Generate an Excel Sample Workbook or to Print a Template and a Samples-to-Be-Analyzed List

Appendix C. Step-by-Step Procedure for Weighing and Storing Samples

Appendix D. Step-by-Step Procedure of Zero Blank Autosampler Operation

Appendix E. Step-by-Step Procedure to Add Sample Information to Sequence Table

Appendix F. Step-by-Step Procedure to Retrieve Data from ISODAT 2.0 for LIMS-LSI and for Data Back-Up

Appendix G. Step-by-Step Procedure to Transfer Data to LIMS-LSI, to Transfer Data to Back-Up Computer, and to Reevaluate Old Data

Appendix H. Step-by-Step Procedure to Determine and Apply Correction Factors and Evaluate Data

Appendix I. Step-by-Step Procedure to Check Elemental Analyzer for Leaks

Appendix J. Daily Checklist

Appendix K. Changing the Insertion Tube

Appendix L. Changing the Water Trap

Appendix M. Changing the Reaction Tube

Appendix N. Step-by-Step Procedure to Report Data

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