Colorado Laboratory for Environmental Mass Spectometry (CLEMS)

The Colorado Laboratory for Environmental Mass Spectrometry (CLEMS) at NREL possesses two isotope ratio mass spectrometers (IRMS) that have been used to analyze diverse solid and gaseious samples for carbon and nitrogen isotopes. We can also determine oxygen isotopes in carbon dioxide. This facility consists of two instruments that are ideal for ecological analyses: one a continuous flow instrument and one a dual-inlet machine.

The facility management maintains the instruments, developes methods and provides training. Each research project provides its own operators to run samples on the instruments. This arrangement helps contain costs as well as providing graduate and undergraduate students valuable hands on experience with the instruments. In the last twelve years, 56 graduate and 21 undergraduate students have used the facility.

CLEMS users within the CSU community come from 7 departments in 4 colleges. The facility has also provided analytical support to students and scientists from 10 other universities worldwide.

VG Isochrom SIRMS

• This continuous flow isotope ratio mass spectrometer made by VG Instruments (Manchester, UK) has two sample preparation systems: an elemental analyzer and a trace gas preconcentrator.

Elemental Analyzer

• The elemental analyzer is a Carlo Erba NA1500 (Milano, IT) which is used for 15N and 13C analysis of solid samples. The most common sample types are soil, vegetation, and animal tissues.
• The minimum sample size for 13C is approximately 1 micromole of Carbon with a typical standard deviation of 0.2 per mill. For 15N, the minimum samples size is approximately 2 micromoles of Nitrogen with a typical standard deviation of 0.3 per mill. Analysis time is approximately 6 minutes per sample.
• An integrated thermal conductivity detector allows the determination of carbon and nitrogen concentrations simultaneously with an isotopic determination.

Trace Gas Preconcentrator

• Designed to measure 13C,18O and 15N in: methane and carbon dioxide at atmospheric concentrations.
• In carbon dioxide mode, 13C and 18O measurements are possible on samples with CO2 concentrations ranging from 300-1000 ppm. Samples as small as 12 mls can be analyzed although 100 mls is recommended. The typical precision is a standard deviation of 0.5 per mill for 13C and 0.6 per mill for 18O.
• In methane mode, 13C can be measured on atmosphere samples (~1 ppm CH4 )as small as 60 mls. At 1000 ppm, samples as small as 1 ml can be measured. The typical precision is a standard deviation of 0.5 per mill. Analysis time is approximately 15 minutes per sample.

VG Optima Dual Inlet SIRMS

• This mass spectrometer can be operated in either dual inlet or continuous flow mode. In dual inlet mode, it features a 10 port manifold with automatic crackers and a multi-prep water equilibration system. In continuous flow mode, it has two prep systems, a pyrolysis system and a microgas injector (packed column gas chromatograph).

Micro-Gas Injector

• This packed column gas chomatograph can be used for measuring CO2 in gas samples or 18O in water samples. For gas samples, direct manual injection allows determination of 13C and 18O of CO2. By varying the injection volume and instrument sensitivity, concentrations ranging from 300 to 60,000 PPM CO2 may be analyzed. The typical precision is a standard deviation of 0.5 per mill for 13C and 0.6 per mill for 18O. Analysis time is approximately 4 minutes per sample.
• The Micro-gas Injector is also used to determine 18O in water by CO2 equilbration. Water is placed in a vial and the headspace is swept with a 10% CO2, 90% He mixture. After a 10 hour equilbration, a Gilson autosampler samples the headspace. The nominal sample size is 0.2 ml. but good precision is acheived with samples as small as 0.05 ml. Up to 40 samples per day may be analyzed with a typical standard deviation of 0.3 per mill.

For More Information: Contact the facility manager, Dan Reuss, Telephone: (970) 491-5573 or email danr@nrel.colostate.edu

The facility director is Joe von Fischer.