HR: 0800h
AN: H11C-1279    [Abstracts]
TI: Real-Time Analysis of Water by Membrane Introduction/Laser Ionization Time-of-Flight Mass Spectrometry
AU: * Oser, H
EM: harald.oser@sri.com
AF: SRI International Molecular Physics Laboratory, 333 Ravenswood Avenue, Menlo Park, CA 94025 United States
AU: Irwin, A
EM: aeirwin@amherst.edu
AF: Amherst College, PO Box, Amherst, MA 01002-5000 United States
AU: Mullen, C
EM: christopher.mullen@sri.com
AF: SRI International Molecular Physics Laboratory, 333 Ravenswood Avenue, Menlo Park, CA 94025 United States
AU: Coggiola, M J
EM: michael.coggiola@sri.com
AF: SRI International Molecular Physics Laboratory, 333 Ravenswood Avenue, Menlo Park, CA 94025 United States
AB: Two photon resonance enhanced multiphoton ionization (REMPI) has been shown to be an unique ionization method for mass spectrometry with high sensitivity and selectivity. This method has been used for about thirty years for fundamental studies in molecular spectroscopy and dynamics, but recently has been examined and developed as a tool for fast, rapid on-line monitoring of complex gas mixtures. The list of reported successful applications includes on-line monitoring of combustion processes, monitoring of automotive exhaust and the formation chemistry of Polychlorinated Dioxins/Furans in waste incineration. At SRI International we are studying the REMPI method for analytical purposes for the determination of trace amounts of hazardous air pollutants, toxics in vehicle exhausts, breath analysis, cancer drugs, and explosives. Since REMPI is a gas phase method, REMPI applications have been limited and applied to gas phase systems or in conjunction with a combination of laser desorption and subsequent laser ionization. We describe here for the first time a combination of MIMS and REMPI with time-of flight mass spectrometry (ToF MS), which allows the direct analysis of water samples. The application of ToF MS offers some advantages like high transmission, robustness, and the ability to record a mass spectrum per each laser shot The objective of this research was the detection of trace amounts of aromatic contaminants particularly BETX in aqueous solutions without interference or clogging of the inlet due to the vastly greater amount of water. To our knowledge, this combination of membrane introduction, laser photoionization and ToF MS has not been examined previously. A significant feature of MIMS is the simultaneous introduction of all analytes into the mass spectrometer. This results in a rapid analytical method, suitable for on-line applications. However, the application of conventional ionization methods presumably electron impact, making the analysis of complex mixtures more difficult. In most MIMS applications, the mass spectrometer has been a standard quadrupole instrument; ion traps and time-of-flight (TOF) devices have also been used. Almost all these studies utilized electron impact ionization. The laser photoionization method, which generally can be adjusted not to photofragment the compounds, allows identification from the parent ion masses only. It offers the advantages both of sensitive, rapid analysis without prior separation or preparation process, and of parent ion mass identification without deconvolution of multiple mass peaks.
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: Fall Meeting 2005