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The Stable Isotope Lab (ENRI SIL) is a state-of-the-art analytical facility that quantifies stable isotope ratios to assist researchers studying processes on short and long time scales. The lab utilizes two ThermoFinnigan Continuous Flow Isotope Ratio Mass Spectrometers (Delta Plus XP and Delta V Advantage) with four gas preparation systems for the measurement of the stable isotopes of carbon, nitrogen, hydrogen, and oxygen (δD, δ13C, δ15N, and δ18O) on a diversity of natural samples (plant, animal, soil, sediment, etc.). The lab also employs three Picarro Wavelength Scanned Cavity Ring-Down Spectrometers for the measurement of the stable isotopes of hydrogen and oxygen in liquid water samples.  The lab is currently capable of accommodating natural abundance samples for all the species mentioned above. ENRI SIL is also able to analyze liquid water samples enriched in δD, δ18O or both.

Operations are conducted by lab manager Dan Crawford. To contact the Stable Isotope Lab, please email uaa_isotope@alaska.edu.

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ThermoFinnigan DeltaPLUS XP and Delta V Advantage – Continuous Flow Isotope Ratio Mass Spectrometers (CF-IRMS) 

The ThermoFinnigan isotope ratio mass spectrometers are fed by four analytical streams. An elemental combustion system for carbon and nitrogen solids analysis (EA) and a temperature conversion elemental analyzer (TC/EA) for oxygen and hydrogen analysis are each connected to an isotope ratio mass spectrometer via a ThermoFinnigan ConFlo III or IV interface.

Picarro Wavelength Scanned Cavity Ring-Down Spectrometer (WS-CRDS)

The Picarro WS-CRDS system utilizes a CTC Analytics PAL autosampler to deliver a liquid water sample via injection into a vaporization chamber. The vaporized water sample is fed into a closed cavity for analysis, during which a discrete quantity of laser light is introduced into the cavity and the absorption curve of the light is used to determine the isotopic makeup of the water sample.

Costech Instruments – Elemental Combustion System (EA)

The EA is used for analysis of δC, δN, δ13C and δ15N in solid samples, including plants, soils, organisms, hair, and sediments. Samples are placed in tin cups and introduced to the elemental analyzer with a zero-blank auto-sampler. The sample is combusted in the presence of oxygen at 1050 degrees Celsius. Combustion gases are then carried in a stream of helium through a reduction column, a water trap and finally a GC column where the gases are separated. Final combustion products N2 and CO2 are introduced to the Delta plus XP by the Conflo lll and δ13C and δ15N are determined. For some δ13Corg analyses, samples are first treated first with HCl to remove carbonates and then dried before placing the samples into tin cups. Costech Instruments EA.

ThermoFinnigan Temperature Conversion Elemental Analyzers (TC/EA)

The two TC/EA is used for sample pyrolysis and continuous flow analysis of 2H and 18O in liquids and solids. Samples are introduced by zero-blank autosampler into the furnace tube and are pyrolyzed at 1450 °C. The component hydrogen and oxygen gases are separated in a GC and are carried to the mass spectrometer in helium gas via a Finnigan Conflo III interface.

Sartorius ME5 and CP2P Microbalances

The Sartorius Microbalances allow users to weigh samples precisely to within 0.001 mg, or 1/100,000 of a gram. This level of precision is necessary for accurate determination of both mass percentage and isotopic composition of a sample. Each microbalance is connected to a computer via a RS-232 interface to allow rapid transfer of weights into electronic sample lists.