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| Techniques and Methods 10–C1 |
(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
This report is available as a pdf.
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:
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(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
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(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.
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
| A. | Step-by-Step Procedure to Log-in Samples to LIMS-LSI. |
| B. | Step-by-Step Procedure to Generate an Excel Sample Workbook or to Print a Template and a Samples-to-Be-Analyzed List. |
| C. | Step-by-Step Procedure to Prepare and Analyze Samples on the Pt Equilibration Line. |
| D. | Step-by-Step Procedure for Hydrogen Mass Spectrometer Checklist. |
| E. | Step-by-Step Procedure to Determine and Apply Correction Factors and Evaluate Data. |
| F. | Step-by-Step Procedure to Report Data. |
(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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