In-Situ Mass Spectrometer (ISMS)
The in situ mass spectrometer (ISMS) is an “open-source” instrument that can measure dissolved gases at depths down to 5000 meters. (Peter Girguis)
An essential component of ecosystems research is characterizing and quantifying the chemical milieu within and around habitats. To date, there is a paucity of chemical sensors that are capable of measuring a wide range of compounds and being left in situ for longer term investigations. Mass spectrometers can measure a broad range of compounds with a single detector. Further, these instruments can have high sensitivity and can handle higher sample throughput.
Accordingly, we developed a membrane inlet mass spectrometer based around a commercially available quadrupole mass spectrometer. The in-situ mass spectrometer (ISMS) is capable of detecting and quantifying volatiles up to 200 daltons at depths down to 4,500 m. Laboratory tests have demonstrated the capacity for use at depths down to 6,000 m. The ISMS can measure parts-per-million concentrations of methane, alkanes, hydrogen, oxygen, hydrogen sulfide, carbon monoxide, carbon dioxide, nitrogen, nitrous oxide and many other volatiles (though these are of particular interest because they are substrates for microbial and macrofaunal metabolism). The ISMS performs well when operated continuously and can be expected to run for 12 to 16 months without servicing (i.e., lubricated or tuned). It is easily integrated on remotely operated vehicles (ROVs) or human occupied vehicles (HOVs) and has been extensively deployed in various marine ecosystems including hydrothermal vents, cold seeps, and deep coral mounds. In addition to campaign-style expeditions, it has been used on cabled and free vehicle observatories for deployments up to 14 months.
