Enhancing Underwater Mass Spectrometry for Ocean Water Exploration Through In-Situ Calibration

A Collaboration with the University of Rhode Island        

In a collaboration with Dr. Brice Loose, Associate Professor of Oceanography at the University of Rhode Island (URI)’s Department of Ocean Engineering, we are contributing to the optimization of their Submersible Wet Inlet Mass Spectrometer (SWIMS) for new exploration campaigns around the Earth oceans, especially those areas that hold key information for climate changing events, such as the polar regions.

URI’s SWIMS, renowned for its unparalleled resolution in measuring volatile compounds, particularly dissolved gases in ocean waters, requires meticulous attention to various instrumental and environmental factors for accurate interpretation of the data collected. The instrument has been field tested at different ocean exploration campaigns characterizing the dissolved gases at key sites in our planet’s ocean system, special around the poles.

The SWIMS used by URI consists of a Transpector® MPH quadrupole mass spectrometer that includes a dual filament and programmable ion source parameters to differentiate gas signals with the same mass peak but different ionization potentials. The system requires a turbo pump system and special membrane inlet to introduce analytes in the water at variable from atmospheric pressure to very high pressures when measuring at significant depths to extract the dissolved gas concentration signals.

The SWIMS design was pioneered by Drs. Tim Short and Strawn Toler, along with other researchers from the University of South Florida, who developed underwater  mass spectrometers (UMSs) and used them in various underwater platforms and vehicles for a variety of research projects. They currently serve as collaborators in this research exploration endeavor in which INFICON is supporting URI with the optimization of a new benchtop mass spectrometer system that uses the state-of-the-art Transpector MPH 200 MS version and will be used for shipboard measurements from collected water samples. This latest version also includes a BCG450 TripleGauge®. This system is ultimately envisioned to be incorporated into a new version of a UMS for future exploration campaigns.

One significant aspect of this collaboration is the development of a new calibration method aimed at measuring and correcting the influence of key variables. These variables include hydrostatic pressure, instrument internal temperature, electronic noise, sample temperature, water vapor, and external water temperature changes. The innovative in-situ calibration method involves continuous sampling from a dissolved gas standard.

UMSs can be used on various platforms, depending on where they need to sample. These platforms include boats, remotely operated vehicles (ROVs), and manned submersibles. The choice of platform depends on factors like the sampling duration and the marine environment being studied, such as the surface ocean, coastal waters, deep ocean, or hydrothermal vents.

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