The Stable Isotope Biogeochemistry lab consists of both a wet chemistry laboratory and instrumentation rooms for gas source mass spectrometry and other analytical equipment, as well as our Cameca ims 7f/geo SIMS instrument for micron-scale analyses.
Secondary Ion Mass Spectrometry (SIMS): Cameca ims 7f/geo
The Cameca 7f/geo arrived on campus in December 2013, and is housed in Rudolph Hall. This instrument is one of the most sensitive surface analysis instruments available, providing materials characterization and compositional analysis with detection limits as low as 1 part per billion and sub-micron-scale spatial resolution. The standard instrument can be configured for spot analysis, depth profiling and ion imaging. This instrument is especially designed for high-precision stable isotope ratio analyses that are particularly germane to our research goals here at Washington University.
The wet chemistry lab is outfitted with multiple fume hoods for the isolation and purification of samples for isotopic analysis. One fume hood is dedicated primarily for carbonate dissolution for analysis of organic carbon and nitrogen isotopes (δ13Corg, δ15Norg) and carbonate-associated sulfate (δ34SCAS), sulfate substituted into the carbonate mineral matrix. Additional fume hoods are dedicated to the extraction of pyrite (δ34Spyr) and acid-volatile sulfur from ancient and modern samples and for the isolation of organic sulfur from samples via Parr bomb. Adjacent facilities exist for microbial growth experiments and microelectrode profiling (e.g., O2, H2S, pH) of modern microbial sediments, cores, and incubations.
Instrumentation Lab: Isotope analysis
Instrumentation in this lab enables bulk geochemical and isotopic analyses of minerals and organic matter.
Major instrumentation includes:
Costech ECS 4010 Elemental Analyzer coupled to a Delta V Plus mass-spectrometer. This instrument is dedicated primarily to sulfur isotope analysis of δ34SCAS and δ34Spyr. A unique series of detectors have been installed to allow for simultaneous measurement of SO2/SO ions at mass/charge ratios of 64,65,66,68 (SO2) and 48,49,50,52 (SO). In theory, this allows for the complete suite of sulfur (and oxygen) isotopes to be measured in SO2. The Delta V can also be tuned to measure the isotopic composition of carbon and/or nitrogen in organic matter (δ13Corg, δ15Norg) and we spend several months a year on these analyses.
Picarro G2121i CO2 analyzer and associated peripherals (Automate carbonate sampler and Liaison interface). This instrument can be used to quantify the concentration and isotopic composition of CO2 in experiments and ambient conditions. Shown on the right is a demonstration for the Clinton Global Initiative meeting held at WashU in April 2013.
Metrohm 881 Compact IC Pro ion chromatograph. This instrument is equipped with both a conductivity and UV/Vis detector for analysis of anions and organic acids. In our lab it is used primarily for analysis of metabolic activity during microbial growth experiments.
Shimadzu GC-2014 gas chromatograph. This instrument can be used to quantify the concentration of gas phase and volatile compounds, especially those produced / consumed during microbial growth experiments.
If you are interested in using these facilities from within the department or WashU, please contact Prof. Fike. For outside users, we can offer commercial isotope analysis with a rapid turn around time.