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POWERFUL NEW TOOLS FOR ANALYZING ENVIRONMENTAL CONTAMINATION: MASS PEAK PROFILING FROM SELECTED-ION RECORDING DATA AND A PROFILE GENERATION MODEL
Citation:
Grange, A H., W C. Brumley, AND G W. Sovocool. POWERFUL NEW TOOLS FOR ANALYZING ENVIRONMENTAL CONTAMINATION: MASS PEAK PROFILING FROM SELECTED-ION RECORDING DATA AND A PROFILE GENERATION MODEL. American Environmental Laboratory 10(7):1,6-7, (1998).
Description:
Capillary gas chromatography with mass spectrometric detection is the most commonly used technique for analyzing samples from Superfund sites. While the U.S. EPA has developed target lists of compounds for which library mass spectra are available on most mass spectrometer data systems, only a small fraction of compounds generated in industrial processes are included in the libraries. Further, the low accuracy of the mass determined for ions can correspond to multiple elemental compositions. Finally, coelution of components can yield poor, multiple matches with library mass spectra. Consequently, comparison of mass spectra with those in libraries cannot identify most components in these complex samples. This applications note discusses a new mass spectrometric approach that overcomes these deficiencies by determining unique compositions for ions, which can lead to identification of otherwise analytically problematic pollutants.
In principle, high-resolution mass spectrometry could be used to determine the exact mass of the molecular ion (M+) from each component, which, if known within narrow error limits, would provide the elemental composition of each compound. The elemental composition of M+ excludes library matches having other compositions and limits a compound's identity to a finite number of isomers. The compositions of fragment ions, and neutral losses determined from their exact masses, can greatly reduce the number of possible isomers, especially when fragment ions characteristic of specific moieties are observed.