Funded by grant EAR-0216179 from the National Science Foundation

What it does: Measures isotope ratios of C, O, and N from geological and biological samples.

How it works: Oxygen, Carbon, or Nitrogen must be separated from samples by some chemical method (such as combustion, dissolution in acids, or fusing with a laser in the presence of an oxidizer). Gasses are then purified in a vacuum line (glass trellis-work in picture) or within the elemental analyzer. The purified gasses are then introduced into the mass spectrometer, either by using the dual-inlet system or continuous flow mode, where they are bombarded by electrons and ionized. The ions travel down a flight tube and are separated according to mass by an electromagnet. The ions are then detected in Faraday cups at the end of the flight tube. The isotope ratio is calculated from the charge of the ions at the end of the flight tube. See Finnigan's brochure for instrument and analytical statistics.
    Although the differences in mass between the isotopes of the light gasses are small (~11% between ¹⁶O and ¹⁸O), the isotope ratio is very sensitive to geological processes. Stable isotopes are commonly used in studies to determine paleoclimate, water-rock interaction, and metamorphic temperatures in rocks, and trophic level and paleodiet in fossils.

Related Research: The lab is currently being used to look at carbon isotopes in maple syrup as a record of atmospheric chemistry and tree health.

Previous Studies:
This lab has been used to determine conditions of metamorphism in the Franklin Marble (NJ) and Morin terrane (Quebec), to understand magnesite ore deposits in Quebec, soils in the Adirondacks, and determine carbon isotope fractionation in apatite. Two projects (still in progress) involved students in constraining metamorphic fluids and temperatures in the Taconic Mountains (Vermont) and Pyrenees Mountains (France).