Posted in | Spectroscopy

New Portable Mass Spectrometer for Remote Location Gas and Water Sample Analysis

A team of Eawag researchers have designed a portable mass spectrometer for carrying out on-site investigation and measurements of environmental gases which previously required months of laboratory study. In addition, a spin-off has been formed for the commercialization of the new spectrometer.

Portable mass spectrometer on Soppensee (Switzerland). (Credit: Eawag)

What is the impact of volcanic gases being collected in Lake Kivu in central Africa? How does the Rhine’s groundwater system function near Pratteln? Is there a better way of controlling the emission of greenhouse gases from a landfill in northeastern Switzerland? Such questions can be answered through “miniRuedi”, a portable mass spectrometer newly designed by the researchers. The new portable mass spectrometer enables real-time and on-site analysis of water and gas samples. For instance, the concentrations of various gases were determined at a landfill as part of a one-day measurement drive. This research underpins the optimization techniques for aerating the landfill to minimize the synthesis of methane, which is a powerful greenhouse gas.

System in a suitcase

Matthias Brennwald, an Eawag environmental physicist who designed the portable mass spectrometer, explained that “Our instrument, weighing 13 kilograms and mounted in a wheeled suitcase, can be taken to the most remote locations. Once it’s been installed on site, the Mini-Ruedi can immediately and efficiently measure gases using very small samples, so it doesn’t interfere with the natural dynamics of the environment.” The system has the ability to operate autonomously and enables continuous quantification of different gases. The most appropriate times and sites for sampling can hence be recognized at once. Moreover, there is also a feasibility of long-term operation.

Analyses which in the past would have been inconceivable—partly for financial reasons, as they’d have involved months of laboratory work—are now suddenly possible.


Two weeks instead of six years

For instance, the Eawag researchers completed a groundwater investigation project in Australia in just two weeks by making use of the miniRuedi. According to Brennwald, if the researchers had used traditional techniques and instruments, it would have taken close to six years to complete in the laboratory. Yet, the measurement accuracy of the new portable mass spectrometer is exceptional as its analytical uncertainty is 1%-3% as against the 1%-1.5% analytical uncertainty of a comparatively high-cost, laboratory-based spectrometer. Maintenance-free operation and low power consumption of 50 watts (equal to that of a conventional light bulb) are the other benefits of the new system. Brennwald reiterated that “for people used to working with measurement instruments, it only takes a day to learn how to handle the portable system.”

Off-the-shelf components

At first look, the new portable mass spectrometer might appear to be complicated, however it only consists of four main components. The incoming gas slowly travels via a capillary tube whose length is 10 m, resembling the trunk of an elephant—the main reason for the name of the system, “Ruedi Rüssel” is a quite familiar chain of petrol stations in Switzerland. Two pumps synthesize the needed vacuum in the chamber in which the gas mixture composition and the abundances of the different gases are evaluated. The electronic “brain” of the system is regulated by software created by Brennwald. The outcomes are fed to a computer from the electronic brain.

When gases in water samples such as lakes have to be investigated, a membrane that isolates the gases from the water is employed, so that the intricate elements in the system are not affected by moisture.

Gasometrix spin-off established

Merely two years following the deployment of miniRuedi for the first time in a project, eight more instruments are being use at present: five instruments at Eawag and four at the Universities of Tübingen and Geneva and at the Mont Terri rock laboratory. Since there have been a number of inquiries, though not related to Eawag projects, received by Matthias Brennwald in connection to buying the system, he decided to start a spin-off, in consultation with Eawag. From April 2017, Brennwald has been creating the portable mass spectrometers under the brand name Gasometrix. Being a devoted employee of Eawag, he stated that this is just a subsidiary. University of Oxford is first client of his own company.

miniRuedi applications all over the world

The miniRuedi has the potential to evaluate a number of environmental gases, which at present include helium, carbon dioxide, argon, oxygen, krypton, methane, and nitrogen. Evaluation of particular gases can assist scientists in gaining an in-depth knowledge on the processes behind gas formation. With dimensions of 60 cm x 40 cm x 14 cm and a weight of 13 kg, the new system is highly compact and can investigate different gases in less than one minute even at remote locations—the reason for the hitherto broad applications of the system. For instance, it has been applied for analyzing water samples to evaluate groundwater systems or to analyze anthropogenic impacts on waterbodies. In a latest assignment in the Czech Republic, investigations of soil samples were performed to analyze gas exhalations from springs. Moreover, further investigations have been planned to be performed for an oil and gas company in Norway: as part of the investigations, gas flows have to be observed to detect the leakage of carbon dioxide or methane.

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