Underwater mass spectrometers for in situ chemical analysis of the hydrosphere

• Published in: Journal of the American Society for Mass Spectrometry Vol. 12; no. 6; pp. 676 - 682
• Main Authors: Short, R.T, Fries, D.P, Kerr, M.L, Lembke, C.E, Toler, S.K, Wenner, P.G, Byrne, R.H
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY Elsevier Inc 01.06.2001; Elsevier Science; Springer Nature B.V
• Subjects: Analysis methods; Analytical chemistry; Applied sciences; Chemical analysis; Chemistry; Dissolved gases; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochemistry; Ions; Lakes; Mass spectrometers; Mass spectrometry; Mineralogy; Natural water pollution; Oceans; Organic compounds; Pollution; Power consumption; Quadrupoles; Scientific imaging; Silicates; Spectrometers; Spectrometric and optical methods; Spectroscopy; Underwater; Wastewater; Water geochemistry; Water treatment and pollution; Trace analysis; Chemical analysis; In situ; Underwater; Instrumentation; Volatile organic compound; Quadrupole spectrometer; Waste water; Ion trap; Dissolved gas; Surface water; Membrane; Portable equipment; Water pollution; Miniaturization; Mass spectrometry; Interface; Seawater
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1016/S1044-0305(01)00246-X

Underwater mass spectrometry systems can be used for direct in situ detection of volatile organic compounds and dissolved gases in oceans, lakes, rivers and waste-water streams. In this work we describe the design and operation of (1) a linear quadrupole mass filter and (2) a quadrupole ion trap mass spectrometer interfaced, in each case, with a membrane introduction/fluid control system and packaged for underwater operation. These mass spectrometry systems can operate autonomously, or under user control via a wireless rf link. Detection limits for each system were determined in the laboratory using pure solutions. The quadrupole mass filter system provides detection limits in the 1-5 ppb range with an upper mass limit of 100 amu. Its power requirement is approximately 95 Watts. The ion trap system has detection limits well below 1 ppb, an upper mass limit of 650 amu and MS/MS capability. Its power consumption is on the order of 150 Watts. The present membrane limits analysis to non-polar compounds (<300 amu) with analysis cycles of 5–15 minutes. Deployments of both types of instruments are described, along with a discussion of the challenges associated with in-water mass spectrometry and descriptions of alternative in-water mass spectrometer configurations.