Skip Links

USGS - science for a changing world

Techniques and Methods 10–C10

Determination of the δ34S of Sulfate in Water; RSIL Lab Code 1951

By Kinga Révész, Haiping Qi, and Tyler B. Coplen

Thumbnail of and link to report PDF (589 KB)Summary

The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1951 is to determine the δ(34S/32S), abbreviated as δ34S, of dissolved sulfate. Dissolved sulfate is collected in the field and precipitated with BaCl2 at pH 3 to 4 as BaSO4 in the laboratory. However, the dissolved organic sulfur (DOS) is oxidized to SO2, and the carbonate is acidified to CO2. Both are degassed from the water sample before the sulfate is precipitated. The precipitated BaSO4 is filtered and dried before introduction into an elemental analyzer (EA) Carlo Erba NC 2500. The EA is used to convert sulfur in a BaSO4 solid sample into SO2 gas, and the EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines the differences in the isotope-amount ratios of stable sulfur isotopes (34S/32S) of the product SO2 gas. The combustion is quantitative; no isotopic fractionation is involved. Samples are placed in a tin capsule and loaded into the Costech Zero Blank Autosampler of the EA. Under computer control, samples are dropped into a heated tube reaction tube that combines the oxidation and reduction reactions. The combustion takes place in a helium atmosphere containing 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. The gas is then introduced into the isotope-ratio mass spectrometer (IRMS) through a Finnigan MAT (now Thermo Scientific) ConFlo II interface, which also is used to inject SO2 reference gas and helium for sample dilution. The IRMS is a Thermo Scientific 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; m/z 66 = SO2 = 34S16O16O primarily.

Revised September 17, 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
http://isotopes.usgs.gov/

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.


Suggested citation:

Révész, Kinga, Qi, Haiping, and Coplen, T.B., 2012, Determination of the δ34S of sulfate in water; RSIL lab code 1951, chap. 10 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, 33 p., available only at https://pubs.usgs.gov/tm/2006/tm10c10/. (Supersedes versions 1.0 and 1.1 released in 2006 and 2007, respectively.)



Contents

Foreword

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 Precipitate BaS04

Appendix C. Step-by-Step Procedure to Create an Excel Sample-List Workbook and Print a Sample List

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

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

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

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

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

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

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

Appendix K. Daily Checklist

Appendix L. Changing the Insertion Tube

Appendix M. Changing the Water Trap

Appendix N. Changing the Reaction Tube

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


Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubsdata.usgs.gov/pubs/tm/2006/tm10c10/index.html
Page Contact Information: GS Pubs Web Contact
Page Last Modified: Friday, 02-Dec-2016 15:46:36 EST