Stable Isotope Laboratory

Principal Investigator: Xiahong Feng

Phone: (603) 646-1642

Isotopic ratios of the elements carbon, nitrogen, oxygen, hydrogen, and sulfur can be routinely measured. Converting a natural sample into gaseous form requires either manual preparation offline or the use of a peripheral device. The lab has glass vacuum lines for manual sample preparation and five peripheral units which automate the preparation of samples and input directly into a mass spectrometer. Types of samples that have been analyzed include water, DIC, snow, soil, soil gas, wood, cellulose, compound specific organic extracts, hair, fish, insects, and carbonates. In addition to the isotope ratio instrumentation, the lab has a DOC/DIC analyzer, a particle size analyzer and hosts glass-blowing facilities.
 
Mass Spectrometers

• Delta+ XL
• Delta+ Advantage

 
Peripheral Devices

• H-Device
  • The H-Device allows for the automatic measurement of hydrogen isotopes in a liquid such as water or an organic extract. The liquid is injected and vaporized at 800-1000°C. The vapors react with chromium to produce Cr₂O₃ and H₂ gas.
• Gas Bench
  • The Gas Bench allows for the automatic measurement of oxygen isotopes in water using CO₂ equilibration method, and in carbonates by their reaction with phosphoric acid. In both cases, CO₂ is sent to an IRMS for isotopic analysis.
• TC/EA
  • The Temperature Conversion Elemental Analyzer is used to analyze oxygen and hydrogen isotopes in wood, cellulose, soil, and liquid samples. The sample is combusted at 400-1500°C in the presence of glassy carbon to produce CO and H₂ for isotopic analysis.
• Carlo Erba EA
  • The Carlo Erba Elemental Analyzer is primarily used to analyze nitrogen, carbon, and sulfur isotopes in wood, soil, animal tissue, and organic extractions. The sample is combusted at 1200°C in the presence of chemical catalysts to produce CO₂, N₂, and SO₂.
• HP 5890 + GCC Interface
  • Utilizing the HP 5890 Gas Chromatograph, it is possible to separate individual organic compounds for isotope ratio measurement. The ability to analyze specific compounds is often necessary to understand the complexities of natural systems. The GCC Interface converts each compound into CO₂ and N₂ through combustion at 940°C.