title: A Portable and Autonomous Mass Spectrometric System for On-Site Environmental Gas Analysis.
abstract: We developed a portable mass spectrometric system ("miniRuedi") for quantificaton of the partial pressures of He, Ne (in dry gas), Ar, Kr, N2, O2, CO2, and CH4in gaseous and aqueous matrices in environmental systems with an analytical uncertainty of 1-3%. The miniRuedi does not require any purification or other preparation of the sampled gases and therefore allows maintenance-free and autonomous operation. The apparatus is most suitable for on-site gas analysis during field work and at remote locations due to its small size (60 cm × 40 cm × 14 cm), low weight (13 kg), and low power consumption (50 W). The gases are continuously sampled and transferred through a capillary pressure reduction system into a vacuum chamber, where they are analyzed using a quadrupole mass spectrometer with a time resolution of ≲1 min. The low gas consumption rate (<0.1 mL/min) minimizes interference with the natural mass balance of gases in environmental systems, and allows the unbiased quantification of dissolved-gas concentrations in water by gas/water equilibration using membrane contractors (gas-equilibrium membrane-inlet mass spectrometry, GE-MIMS). The performance of the miniRuedi is demonstrated in laboratory and field tests, and its utility is illustrated in field applications related to soil-gas formation, lake/atmosphere gas exchange, and seafloor gas emanations.
authors.affiliation: Department of Water Resources and Drinking Water, Eawag, Swiss Federal Institute of Aquatic Science and Technology , Dübendorf, Switzerland.
authors.forename: Matthias S
authors.identifier: 0000-0003-1103-8699
authors.initials: MS
authors.lastname: Brennwald
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel , Wischhofstrasse 1-3, 24148 Kiel, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Department of Water Resources and Drinking Water, Eawag, Swiss Federal Institute of Aquatic Science and Technology , Dübendorf, Switzerland.
authors.forename: Julian
authors.initials: J
authors.lastname: Oser
authors.affiliation: Department of Water Resources and Drinking Water, Eawag, Swiss Federal Institute of Aquatic Science and Technology , Dübendorf, Switzerland.|Institute for Geochemistry and Petrology, ETH Zurich , Zurich 8092, Switzerland.
authors.forename: Rolf
authors.initials: R
authors.lastname: Kipfer
mesh_terms: D005740:Gases; D060106:Lakes; D013058:Mass Spectrometry; D012987:Soil; D014867:Water
chemical_list: D005740:Gases; D012987:Soil; D014867:Water