title: Membrane introduction/laser photoionization time-of-flight mass spectrometry.
abstract: Two-photon resonance enhanced multiphoton ionization (REMPI) has been shown to be a unique ionization method for mass spectrometry, exhibiting both high sensitivity and chemical selectivity. Because REMPI is a gas-phase method, its applications have been limited either to direct analysis of vapor phase samples, or in conjunction with an initial laser desorption or other vaporization step. We describe here for the first time a combination of membrane introduction mass spectrometry (MIMS) and REMPI with time-of-flight mass spectrometry (TOF-MS), which allows for the direct analysis of trace amounts of organic compounds in water samples. The objective of our research was the detection of very low levels of aromatic contaminants, particularly benzene, toluene, and xylene (BTX), in aqueous solutions without interference due to the water. We have measured limits of detection (LOD) for selected aromatics in water below 1 part-per-trillion with an averaging time of less than 10 s using a continuous sample flow.
authors.affiliation: Molecular Physics Laboratory, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA. harald.oser@sri.com
authors.forename: Harald
authors.initials: H
authors.lastname: Oser
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Coggiola
authors.forename: Steven E
authors.initials: SE
authors.lastname: Young
authors.forename: David R
authors.initials: DR
authors.lastname: Crosley
authors.forename: Virginia
authors.initials: V
authors.lastname: Hafer
authors.forename: Gregory
authors.initials: G
authors.lastname: Grist
mesh_terms: D001554:Benzene / Q000032:analysis; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods*; D006841:Hydrocarbons, Aromatic / Q000032:analysis*; D007834:Lasers; D008567:Membranes, Artificial; D010777:Photochemistry; D017785:Photons; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors; D014050:Toluene / Q000032:analysis; D014867:Water / Q000032:analysis; D014992:Xylenes / Q000032:analysis
chemical_list: D004785:Environmental Pollutants; D006841:Hydrocarbons, Aromatic; D008567:Membranes, Artificial; D014992:Xylenes; D014867:Water; D014050:Toluene; D001554:Benzene