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USING AN ACCURATE MASS, TRIPLE QUADRUPOLE MASS SPECTROMETER AND AN ION CORRELATION PROGRAM TO IDENTIFY COMPOUNDS
Citation:
GRANGE, A. H., W. WINNIK, P. L. FERGUSON, AND G. SOVOCOOL. USING AN ACCURATE MASS, TRIPLE QUADRUPOLE MASS SPECTROMETER AND AN ION CORRELATION PROGRAM TO IDENTIFY COMPOUNDS. Presented at 53rd Annual American Society for Mass Spectrometry Meeting, San Antonio, TX, June 05 - 09, 2005.
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:
Most compounds are not found in mass spectral libraries and must be identified by other means. Often, compound identities can be deduced from the compositions of the ions in their mass spectra and review of the chemical literature. Confirmation is provided by mass spectra and retention time comparisons between analytes and purchased standards.
Two independent physical properties distinguish among ion compositions possible for a given nominal mass: the exact masses of ions and the relative isotopic abundances (RIAs) of ions greater in mass by 1 and 2 Da that arise from the presence of atoms of heavier isotopes of elements, e.g., 13C, 2H, 15N, 17O, 18O, 33S, 34S, 37Cl, and 81Br.
Instrumental capabilities that constrain the utility of a mass spectrometer for measuring exact masses and RIAs of ions from compounds that elute into the ion source from a chromatographic column are scan speed, mass accuracy, linear dynamic range, and resolving power.(1) For the past decade, our laboratory has used double focusing mass spectrometers in the selected ion recording mode to determine ion compositions.(2-4) Our analytical methodology, Ion Composition Elucidation (ICE), requires up to three experiments using custom software written in macro languages available for VG 70SE or Finnigan MAT900 mass spectrometers, but not for newer instruments.
Fortunately, other types of mass spectrometers can now provide mass accuracies and linear dynamic ranges sufficient to determine ion compositions using scan modes provided by the manufacturers. Herein, the utility of an accurate mass triple quadrupole mass spectrometer for identifying compounds is demonstrated.