Stable Isotope Laboratory
Mission Statement
The Stable Isotope Laboratory is intended to be a hands-on teaching
and research facility for the students and faculty at Iowa State University.
The laboratory is devoted to performing continuous-flow isotopic (‰)
and elemental (%) analyses of carbon (C), nitrogen (N), oxygen (O) and
hydrogen (H) in organic and inorganic substrates (solids, liquids, and
gases). The lab supports research in different disciplines, including
geology, ecology, agronomy, and chemistry. In addition, analyses of
samples for other interested researchers are also performed in the lab.
The laboratory consists of a ThermoFinnigan Delta Plus XL mass spectrometer
coupled with several sample introduction systems, including a GasBench
II with a CombiPal autosampler, a Costech elemental analyzer and a TC/EA
with a Conflo III interface. In addition, the laboratory houses a number
of facilities intended to aid in the preparation and purification of
samples for isotopic and elemental determinations. These facilities
include a ballmill grinding device, a freeze-dryer, solvent-extraction
apparatus, and vacuum glass lines.
Instrumentation
The completely modernized stable isotope ratio mass spectrometry facility
at Iowa State University includes a new Finnigan MAT Delta Plus XL mass
spectrometer with both dual inlet and continuous flow systems. The mass-spectrometer
is configured for high-precision isotope ratio analyses of hydrogen,
nitrogen, carbon, and oxygen. These analyses are performed on hydrogen,
oxygen, nitrogen, and carbon monoxide and dioxide generated from biological
and geological substrates. Peripheral devices attached to the Delta
Plus XL allow rapid and automated generation of gases introduced into
the mass-spectrometer for isotopic determinations. These devices include:
A Costech Elemental Analyzer with zero-blank autosampler
for the analyses of bulk organic carbon and nitrogen isotopes in plant
materials, soils, sediments, and rocks.
A Gas Bench with a CombiPAL autosampler for the automated
analyses of oxygen isotopes in water, carbon and oxygen isotopes in
carbonates, and carbon isotopes in dissolved inorganic carbon. In addition,
the device allows isotopic determinations of oxygen and carbon isotopes
in atmospheric or purified carbon dioxide.
A TC/EA (thermochemical elemental analyzer) with zero-blank
autosampler for the automated analyses of oxygen isotopes in nitrates,
sulfates, and phosphates. This device also allows the determination
of hydrogen isotopes in water and organic samples.
