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Techniques and Methods 10–C1

Determination of the (2H/1H)of Water: RSIL Lab Code 1574

U.S. Geological Survey

By Kinga Révész and T.B. Coplen

Chapter 1
Section C, Stable Isotope-Ratio Methods
Book 10, Methods of the Reston Stable Isotope Laboratory

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Summary of Procedure

Reston Stable Isotope Laboratory (RSIL) lab code 1574 describes a method used to determine the relative hydrogen isotope-ratio δ(2H,1H), abbreviated hereafter as δ2H, of water. The δ2H measurement of water also is a component of the National Water Quality Laboratory (NWQL) schedules 1142 and 1172. The water is collected unfiltered in a 60-mL glass bottle and capped with a Polyseal cap. In the laboratory, the water sample is equilibrated with gaseous hydrogen using a platinum catalyst (Horita, 1988; Horita and others, 1989; Coplen and others, 1991). The reaction for the exchange of one hydrogen atom is shown in equation 1:

               pic3      (1)

The number ratio N(2H)/N(1H) of the equilibrated hydrogen is related to that of the water through an isotopic fractionation factor ahydrogen gas,water

            Symbols      (2)

The value of ahydrogen gas,water is constant at a given temperature. Because reference waters and unknowns are interspersed and analyzed at the same temperature, the isotopic fractionation factor cancels and does not need to be known. Water and platinum catalyst are placed in glass tubes on a manifold in the equilibration system. The temperature in the equilibration system is held constant to keep the isotopic fractionation constant between gaseous hydrogen and water samples and references. Under computer control, the air from each sample vessel is exhausted, and the vessels are filled with gaseous hydrogen. The equilibrated hydrogen from each sample vessel is expanded under computer control into a dual inlet isotope-ratio mass spectrometer (DI-IRMS), which determines stable hydrogen isotopic composition. The RSIL uses a VG Micromass 602 hydrogen isotope-ratio mass spectrometer (IRMS). It has two Faraday cup collectors and is capable of measuring mass/charge (m/z) 2 and 3 simultaneously. The ion beams from H2 are as follows: m/z 2 = H2+ = 1H1H+; 3 = H2 = 2H1H+ and 1H1H1H+. The isotopic compositions of unknowns are determined by normalizing data to that of isotopic reference waters analyzed with unknowns.

Table of Contents

Forward

Conversion Factors

Acronyms, and Abbreviations

Symbols

Summary of Procedure

Reporting Units and Operational Range

Reference Materials and Documentatione

Reference Materials Used, Storage Requirements, and Shelf Life

Documentation

Labware, Instrumentation, and Reagents

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

Sample Containers, Preservation, and Handling Requirements

Sample Preparation and Time Requirements

Performing the Analysis and Time Requirements

Problematic Samples

Interferences

Troubleshooting and Bench Notes

Maintenance and Maintenance Records

Sample Retention Time and Disposal

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

Laboratory Information Management System for Light Stable Isotope (LIMS-LSI)

Quality-Control (QC) Samples

Acceptance Criteria for all QC Samples

Corrective Action Requirements

Responsible Parties for All QA/QC Functions for Procedures Covered in RSIL SOPs

Data Management and Records

Health, Safety, and Waste-Disposal Information

Applicable Health and Safety Issues

Personal Protection

Electrical Hazards

Chemical Hazards

Gas Cylinder Handling

Biological Hazard

Specific Waste-Disposal Requirements

Revision History

References Cited

Apendixes

Suggested citation:
Révész, Kinga, and Coplen, T.B., 2008, Determination of the snake(2H/1H) of water: RSIL lab code 1574, chap. C1 of Révész, Kinga, and Coplen, T.B., eds., Methods of the Reston Stable Isotope Laboratory: U.S. Geological Survey Techniques and Methods 10–C1, 27 p.

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