MAT Delta Plus
houses a Finnigan MAT Delta Plus that was purchased in 1997. This isotope
ratio mass spectrometer (IRMS) has the ability to measure samples for 13C / 12C and 15N / 14N. Currently, the instrument is plumbed
to a Carlo Erba NC2500 elemental analyzer through a Conflo II open split interface
for elemental and isotopic composition of solid samples. The elemental
analyzer is equipped with a low blank AS200 auto-sampler with sample-throughput capabilities.
18O / 16O measurements from liquid samples are measured using a temperature-controlled water equilibration unit. This peripheral device is capable of robust isotope ratio measurements via a process known as dual inlet analysis. 24 samples can be analyzed during the course of a sample run using 3 ml aliquots.
Measurement of gas samples is done on the tube-cracker multiport system. The multiport is another form of dual inlet analysis that can measure prepped samples for N2, CO2, and H2 gases. These samples must be vacuum-sealed in glass tubes. COIL has the extraction lines, which are utilized for most multiport sample needs. Currently we are not accepting external samples for this type of analysis and internal sample analysis needs prior approval from the Laboratory Manager.
1-70 dalton at 3 KV
CNOS: M/deltaM = 95 (10% valley definition)
H/D: M/deltaM = 10 (10% valley definition)
1500 molecules CO2 per mass 44 ion at the collector with high Helium
flow (1500 molecules/ion)
Ion Source Linearity:
0.02‰/nA ion current (mass 44)
Sample Consumption (typical):
0.15 nmol/s CO2 for 10 nA signal at mass 44 (10-2)
Thermo Delta V Advantage Isotope Ratio Mass Spectrometer
The Thermo Delta V Advantage IRMS was installed in 2006, along with a Temperature Conversion Elemental Analyzer (TC/EA). In subsequent years two additional devices (a Gasbench II and a PreCon) have been added to meet the needs of varying isotopic research.
The ConFlo III Interface allows the connection of a wide variety of elemental analyzers to the DELTA V including quantitative high temperature carbon reduction elemental analyzers for D/H and 18O/16O (TC/EA). The automated dilution system of the ConFlo III, together with the 50 Volt amplification range of the DELTA V allow dual element analysis of H and O with a dynamic range > 1:1000. Solid samples are introduced to the combustion column via a Costech Zero-Blank autosampler.
The GasBench II is a continuous flow preparation device and inlet system with repetitive loop injection of gases. Supported by a GC-PAL autosampler and using septum-sealed sample vials, a wide variety of applications is accessible for high precision on-line measurements. The GasBench II connected to a DELTA V offers precision comparable to dual inlet methods for H2 and CO2 water equilibration, CO2 from air, and dissolved inorganic carbon but with the enhanced productivity and ease-of-operation of Continuous Flow Isotope Ratio MS. Although the Gasbench II is capable of several measurement types we are currently using it for analysis of CO2 (ambient to 10,000ppm) and N2 (enriched 15N up to 2 Atom%) gases only.
Trace Gas Analysis
The PreCon trace gas pre-concentrator can be connected to the GasBench II for atmospheric trace-gas research in the ppm and ppb range. Typical gases measured using this device include methane (CH4) and Nitrous oxide (N2O). Currently this application is being used for internal research and calibration; which means we are not accepting outside samples for the time being.
DELTA V System Performance
SensitivityContinuous Flow mode
Molecules CO2 / mass 44 ion with Isotope Ratio Linearity* 0.02 ‰ / nA
Mass Range 1 – 96 Dalton 1 – 80 Dalton at 3 kV
Mass Resolution 110m/Δm (10 % valley)
Effective Magnetic 191 mm Deflection Radius
System Stability < 10 ppm
H3+ Factor < 10 ppm / nA
H3+ Factor Stability < 0.03 ppm / nA / h
Noise Level < 50 dB(A)
*Known as Ion Source Linearity