The Stable Isotope Laboratory at EcoCore (EcoCore-IsoLab) is a service, research and teaching facility for the study of isotopes in ecology and environmental sciences. Analyses are performed by researchers themselves or by EcoCore, and charged per sample. The facility provides students and researchers valuable hands-on experience with the instruments, and assists CSU faculty in facilitating labs for isotope-related classes and workshops. Click here for some of the educational support provided by the lab.
CSU-IsoLab possesses three isotope ratio mass spectrometers (IRMS), several interfaces and preparation systems that enable isotope analyses of different elements (C, N, O, H) in solid, liquid and gas at atmospheric and trace concentrations. The facility management maintains the instruments, develops methods and provides training. Within the lab, an area is designed for teaching, research seminars and small workshops, which can be used by CSU faculty.
Analytical capabilities and equipment:
- Solid sample 13C and 15N analysis
- 13C analysis of CO2 in concentrated samples
- 18O analysis of water
- Trace gas isotope analysis
- Compound-specific stable isotope analyses
Solid sample 13C and 15N analysis by Carlo Erba NA 1500 (Milano, IT) elemental analyzer coupled to a VG Isochrom continuous flow IRMS (Isoprime Inc., Manchester, UK). An integrated thermal conductivity detector (TCD) also allows the determination of carbon and nitrogen concentrations simultaneously with an isotopic determination. Each analysis (13C or 15N) requires one sample.
|Observed precision||0.2 ‰||0.3 ‰|
|Minimum sample size*||1 umol C||2 umol N|
|Run time/sample||6 min||6 min|
|*Click here to download our sample size calculator|
|Observed precision||0.4 ‰|
|Minimum sample size||2000 ppm CO2|
|Run time/sample||3 min|
18O analysis of water by CO2 equilibration (equilibration block) and micro-gas Injector with auto-sampler coupled to a VG Optima IRMS (Isoprime Inc., Manchester, UK). The lab also has a vacuum line for extracting water from soils and plant tissues.
|Observed precision*||0.3 ‰|
|Nominal sample size||0.2 mL|
|Capacity (max. samples/day)||40|
|* Smaller samples may be analyzed with some loss of precision. Click here to see the graph of precision vs. sample size.|
Trace gas isotope analysis (i.e. CO2, N2O and CH4) by Thermo PreCon coupled to a Delta V IRMS (Thermo Scientific). The PreCon is a fully automated trace gas pre-concentrator for the isotope characterization of N2O, CH4 and CO2 at natural concentrations. Following manual gas injection, the PreCon carries out sample concentration, purification, cryofocusing, and injection onto a gas chromatograph prior to IRMS analysis. Currently configured for 13C analysis of CO2 at atmospheric concentrations.
|13C analysis of CO2|
|Observed precision*||0.2 ‰|
|Sample size range||0.007 – 0.021 umol CO2|
|Run time/sample||15 min|
|* Standard deviation of 34 injections over 3 running days|
Compound-specific stable isotope analyses by a Thermo GC-c/py-IRMS system composed of a Trace GC Ultra gas chromatograph with TriPlus autosampler, GC IsoLink Unit, coupled to a Delta V Advantage IRMS through a ConFlo IV universal interface (Thermo Scientific). FAME identification support is provided by GC-MS (Thermo Scientific Trace DSQ) at the PMF Core Facility at CSU. The instrument allows for the determination of 18O and 2H on CO and H2 generated by pyrolysis (1450°C), and 13C and 15N on CO2 and N2 generated by combustion (1030°C). The instrument is currently configured for 13C analysis in fatty acid methyl esters (FAMEs). FAMEs dissolved in hexane are injected in splitless mode and separated on a DB-5 column (30m x 0.25mm ID x 0.25um film thickness). δ13C values are corrected using C12:0 and C19:0 working standards calibrated against NIST standard reference materials.
|13C analysis of FAMEs|
|Observed precision*||0.4 ‰|
|Sample size range||5-150 ng C (per FAME)|
|Run time/sample||approx. 1h|
|* Based on 16 replicate injections of a C19:0 standard. Precision is greatly affected by peak separation.|