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UTILITY OF THREE TYPES OF MASS SPECTROMETERS FOR DETERMINING ELEMENTAL COMPOSITIONS OF IONS FORMED FROM CHROMATOGRAPHICALLY SEPARATED COMPOUNDS
Citation:
Grange, A H., F. A. Genicola, AND G W. Sovocool. UTILITY OF THREE TYPES OF MASS SPECTROMETERS FOR DETERMINING ELEMENTAL COMPOSITIONS OF IONS FORMED FROM CHROMATOGRAPHICALLY SEPARATED COMPOUNDS. RAPID COMMUNICATIONS IN MASS SPECTROMETRY 16(24):2356-2369, (2002).
Impact/Purpose:
Provide state-of-the-science sampling, analysis, separation, and detection methods to allow rapid, accurate field and laboratory analyses of contaminated soils, sediments, biota, and groundwater to support Superfund clean-up decisions. Apply state-of-the-science methods in chemical analysis and data interpretation (e.g., mass spectral interpretation) to actual problems of OSWER, the Regions, and the States, in cooperation with the Las Vegas Technical Support Center as well as by direct contacts with Regional and State employees. Provide technical advice and guidance to OSWER using the environmental chemistry expertise (e.g., mass spectrometry, analytical methods development, clean-up methodology, inorganics, organometallics, volatile organics, non-volatile organics, semi-volatile organics, separation technologies, etc.) found within the branch.
Technical research support for various projects initiated either by Regions/Program Offices or ECB scientists. While these efforts will support the Regions and Program Offices, they cannot be predicted or planned in advance, and may serve multiple duty (e.g., solve real-world problems, serve to ground-truth analytical approaches that ECB is developing, transfer new technology). Many of the activities in this task support requests involving enforcement decisions and therefore are categorized as "environmental forensics".
Description:
Sponsor Referee: Douglas F. Barofsky, Oregon State University Concentration factors of 1000 and more reveal dozens of compounds in extracts of water supplies. Library mass spectra for most of these compounds are not available, and alternative means of identification are needed. Determination of the elemental compositions of the ions in mass spectra makes feasible searches of commercial and chemical literature that often lead to compound identification. Instrumental capabilities that constrain the utility of a mass spectrometer for determining ion compositions for compounds that elute from a chromatographic column are scan speed, mass accuracy, linear dynamic range, and resolving power. Mass Peak Profiling from Selected Ion Recording Data (MPPSIRD) performed with a double focusing mass spectrometer provides the best combination of these capabilities. This technique provides unique ion compositions for higher mass ions than data acquired with orthogonal acceleration time-of- flight (oa-TOF) or Fourier transform ion cyclotron resonance mass spectrometers. Multiple compositions are usually possible for an ion with a mass exceeding 150 Da within the error limits of the mass measurement. The correct composition is selected based on measured exact masses of the profiles higher in mass by I and 2 Da and accurate
measurement of the summed abundances of the isotopic ions contributing to these two profiles relative to the monoisotopic ion. A Profile Generation Model (PGM) automatically determines which compositions are consistent with measured exact masses and relative abundances. The utility of oa-TOF and double focusing mass spectrometry using Ion Composition Elucidation (MPPSIRD plus the PGM) are considered for determining ion compositions of two compounds found in drinking water extracts and a third compound from a monitoring well at a landfill.