Noble Gas Mass Spectrometry

Located within the Water Dating Laboratory, the mass spectrometers measure noble gas concentrations (He, Ne, Ar, Kr and Xe) and isotope ratios in minerals, fluids, and gas samples. This data can be used to better understand a range of processes in groundwater, volcanology, geochronology, paleoclimate, and in crustal, hydrothermal and ore fluids.

Our equipment

• Sample degassing bench 

  - a purpose-built vacuum line for manually extracting and cryogenically concentrating gas from water samples. Water samples collected in 3/8” copper tubes are degassed under vacuum and the sample gas is isolated onto a stainless steel sample vial using liquid nitrogen and a 0.5 mm capillary to prevent backflow and loss of sample gas. 

• Noble Gas purification system – an automated system for inletting the isolated sample gas, removing water vapor using a 2-stage cryogenic water trap (similar to the design by Stanley et al., 2009), removing reactive gases with Ti-sponge furnaces, SAES® getters, and a Pd + CuO furnace, and freezing Ne, Ar, Kr, and Xe onto a computer-controlled cryotrap. Each of the noble gases can be released and inlet into the Hiden quadrupole and/or the Helix MC mass spectrometer for analysis.
• Hiden HAL 3F-PIC Quadrupole Mass Spectrometer - for measurement of noble gas (He, Ne, Ar, Xe, and Kr) concentrations in gas and water samples. This system is equipped with a pulse-counting (PIC) electron multiplier for increases sensitivity. The noble gas purification system and Hiden quadrupole mass spectrometer are primarily designed for quantifying denitrification-products (i.e., excess N₂) in groundwater systems, with the capability to measure noble gas concentrations to better than 1% analytical error. This system can also be used for many other applications, including analysis of geothermal fluids, seawater, pore-water, etc. 
• Helix MC multicollector Noble Gas Mass Spectrometer – for high-precision isotope ratio measurements of noble gas (He, Ne, Ar, Xe, and Kr). The Helix MC+ is a magnetic sector mass spectrometer with high mass-resolution so that measurements can avoid isobaric molecular and double-charge interferences. Coupled with the high-sensitivity detectors, this permits highly stable and precise measurements of noble gas isotopic ratios, which are necessary to resolve small differences in natural isotope ratios caused by processes in groundwater, surface water, hydrothermal fluids and/or minerals that fractionate and/or concentrate specific isotopes naturally in these systems.