STABLE ISOTOPES NITROGEN 15 Equipment

MAT 252, purchased in 1992, is an automated multi-purpose gas source isotope-ratio mass spectrometer used for analyzing carbon, hydrogen, sulfur, oxygen and nitrogen isotopes. The instrument is equipped with a microvolume for samples as small as 100 nanomoles and a cracker device for automated processing of gasses in 6mm closed tubes. Attached to the MAT 252 are two peripherals: A trapping box for the automated preparation of CO2 from carbonates, combusted organic samples, or water CO2 equilibrations. Gas chromatograph/open split interface that allows for isotopic analyses of ultra small (<10 nanomoles) samples of CO2, N2, and SO2 using state-of-the-art gas chromatograph isotope-ratio monitoring mass spectrometry (GC-IRMS) techniques. VG Optima, purchased in 1996, is a fully automated gas source IRMS with 5 collectors suitable for carbon, oxygen, nitrogen, hydrogen, and sulfur isotope analyses. Installed in February 1997, this instrument is equipped with 10 cracker tube inlet ports, a multiprep unit for automated CO2-water equilibration oxygen isotope measurements and carbonate acid digestion CO2 isotope analyses of 60 samples each loading, a multi-element analyzer for total combustion and analysis of carbon and nitrogen from the same sample sequentially, and/or sulfur isotope analyses all automated with a 50 sample carousel (approximately 5 minutes/analysis - 100 samples/day). The inlet manifold is equipped with a small automated sample cold finger to process samples with CO2 yields of several hundred nanomoles. Located in Denver. Additional Special Equipment: Microsampler (computerized drill capable of 10 micron spatial resolution) CO2 laser/microscope for microbeam sampling and isotopic analysis (60 micron minimum beam diameter) - mid infrared. Nd:YAG laser/microscope for microbeam sampling and isotopic analysis (15-20 micron minimum beam diameter) - near infrared. Cold lab maintained at -30 °C for ice and biologic materials. VG Element Analyzer - carbon and nitrogen or sulfur from same microgram sample. Multiprep - automated carbonate (functionally replicates Kiel device) or water oxygen equilibration or water hydrogen equilibration. GC Capillary OpenSplit Interface - continuous flow CO2 and SO2 isotopic analysis from gas chromatograph through capillaries. Fluorination lines (BrF5 and F2) - unique to only several labs in world (no commercial facilities available). Hydrous mineral/fluid inclusion/water hydrogen - unique to this lab.

| Capabilities | | Geochronology, Geochemistry, and Tracer Studies  | | Geochemistry, and Tracer Studies  |

URL http://geology.cr.usgs.gov/capabilities/gronemtrac/geochem/stablei/nitrogen/equip.html