Instrumentation

Vathi (Thermo Finnigan Delta V)

This instrument is used for carbon, nitrogen, and sulfur isotope analysis of solid samples. The ISOTOPE cube elemental analyzer peripheral uses a unique purge and trap method for C, N, H, S analysis of a single sample. The mass spectrometer has been equipped with a special collector array for the simultaneous analysis of SO₂ and SO, which allows for oxygen isotope effects to be corrected for during analysis.

Kioni (Thermo Finnigan Delta V)

This is a multi purpose instrument which has been setup to run isotopic analyses of waters, carbonates, dissolved inorganic carbon (DIC) and nitrates. The Gasbench is used along with the equilibration method for oxygen and hydrogen isotope analysis of waters. Carbon and oxygen isotope analysis of carbonates using the phosphoric acid digestion is also conducted on the Gasbench. Eventially site-specific nitrogen isotope analysis of nitrates will also be performed by simultaneously analyzing N₂O and NO.

Quadra (Thermo Finnigan MAT 253)

For compound specific carbon and hydrogen isotope analysis (e.g. δ¹³C and δD (δ²H) of alkanes, δ¹³C and δ¹⁸O of CO₂, etc.). In addition, a dual inlet sample introduction system allows for the analysis of gas samples prepared offline.

Compound specific isotope analysis provides unique insights into elemental cycling and fingerprinting in specific organic compounds. For carbon isotope analysis samples are injected into the Trace GC where they are volatized, then separated by gas chromotography before they are combusted in a furnace of the GC Isolink to create CO₂which is then analyzed by the mass spectrometer. For hydrogen isotope analysis samples undergo similar GC followed by pyrolysis into H₂.

Pyro (Thermo Finnigan Delta V)

For triple oxygen isotope and nitrogen isotope analysis of nitrates. This instrument is equipped with a modified PreCon which allows for the analysis of oxygen and nitrogen isotopes in nitrates. Nitrate samples are innoculated into a bacterial culture which consumes the nitrate and produces N₂O (see Sigman et al., 2001 for more info). N₂O is then decomposed in a gold oven to create N₂ and O₂ which are separated and concentrated in the GC-PreCon system before analysis in the mass spec.

Uno (Thermo Finnigan Delta+ XL)

This instrument is equipped with several peripherals capable of hydrogen, carbon, nitrogen, oxygen, and sulfur isotope analysis of solid and gas samples. The HEKAtech is used to pyrolyze (thermally decompose without oxygen) samples at higher temperatures than the TC/EA, which is useful for the analysis of phosphates and florinated compounds. The TC/EA also pyrolyzes samples at slightly lower temperatures and is useful for oxygen isotope analysis of briny waters and sulfates. Fisons NA1500 elemental analyzer is used for sulfur isotope analysis of both sulfides and sulfates.

Alaska (Thermo Finnigan Delta+ XL)

The workhorse. This instrument with its attached Costech EA is used for carbon and nitrogen analysis of solid samples. Soils, fertilizers, sediments, organic matter, ammonia, etc. Samples are combusted to create CO₂ or N₂ which is then analyzed in the mass spectrometer.

Los Gatos Research Water Isotope Analyzer

This laser based instrument is used for hydrogen and oxygen isotope analysis of waters. The instrument uses the Cavity-Ringdown Spectroscopy (CRDS) technique to determine the isotopic composition spectroscopically as opposed to traditional mass spectrometry.

Picarro G2201-i Carbon Isotope Analyzer

Also a laser based instrument utilizing the same CRDS technique for carbon isotope analysis of carbon dioxide and methane samples at near ambient concentrations.

Isotope Science Lab