Gas, elemental and organic compound analysis

Analysis of gases, nutrients, metabolic products and organic compounds in environmental samples, porewaters, or cultures is performed using different photometric, gas and liquid chromatographic, mass spectrometric, or microsensor, techniques.

Dissolved gases

Ratios of dissolved gases (N2/Ar/O2) are measured directly in water samples using a membrane-inlet mass spectrometer (MIMS) (Bay Instruments, Easton, Maryland, USA).

 

Methane and nitrous oxide concentrations in water samples are measured by headspace analysis using a gas chromatograph with flame ionization (GC-FID for CH4) or electron capture detector (GC-ECD for N2O).

Nutrients, solutes, dissolved organics

For the concentration measurement of nutrients and major ions we use standard ion chromatographic and colorimetric methods. A multi-detector gradient HPLC system is used for the analysis of sugars, organic acids or intermediate oxidized sulfur species. For high-resolution solute profiling (e.g.,O2, H2S, pH) in sediment porewaters and microbial mats we use computer-motorized amperometric and potentiometric microsensors.

Organic compound identification and quantification

We have dedicated workspace for the extraction, separation and derivatization of organic compounds. For quantification and identification of individual (lipid) compounds is performed we use a gas chromatograph equipped with a split/splitless injector, a FID, and a quadrupole MS detector.

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Equipment

  • MIMS (Pfeiffer Prisma Quadrupole MS system; 1-100 amu)
  • GC-FID/GC-ECD (SRI 8610C, SRI Instruments)
  • Trace GC Ultra (Thermo Fisher Scientific) with quadrupole MS detector (Thermo Fisher Scientific DSQ II)
  • NOx Analyzer (Antek Model 745)
  • Metrohm 940 Professional IC Vario System with conductivity and UV detection (installation in March 2014)
  • Spectrophotometer (Perkin Elmer, Lamda XLS)
  • Gradient HPLC system (Dionex ED 40) with electrochemical (Dionex ED 40), absorbance (Waters 486), and fluorescence (Waters 470) detectors
  • pH Meter (Mettler Toledo, Seven Compact)
  • Microsensor set-up (Unisense) with motorized micromanipulator and multimeter for amperometric and potentiometric sensors.

As a copartner, we also have access to a XRF core scanner (ITRAX) installed at the University of Bern (Prof. Dr. F. Anselmetti). Scanning XRF analysis is a non-destructive analytical method in limnogeological studies that allows the assessment of the chemical composition of sediments at very high spatial, and thus temporal, resolution.