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Identification of Compounds in South African Stream Samples Using Ion Composition Elucidation (Ice)

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Abstract:Analytical methods for target compounds usually employ clean-up procedures to remove potential mass interferences and utilize selected ion recording (SIR) to provide low detection limits. Such an approach, however, could overlook non-target compounds that might be present and that could pose risks to ecosystems or to humans. In an ideal world, it would be preferred that all compounds present be identified, quantified, and evaluated for toxicity.

The US EPA's Environmental Chemistry Branch is identifying as many compounds as possible in several stream samples collected near Johannesburg, South Africa, using Ion Composition Elucidation (ICE), a high resolution mass spectrometric technique developed in-house. This SIR based technique measures the exact masses of an ion and its +1 and +2 mass peak profiles that arise from heavier isotopes such as 13C, 2H, 15N, 17(, 180, 33S, and 34S. The abundances of the +1 and +2 profiles relative to the monoisotopic ion's profile are also measured for compounds that provide gas chromatographic peaks. Comparison of measured and calculated values of these three exact masses and two relative abundances for the ion compositions that are possible based on the ion's exact mass and its error limits provides unique compositions for the ions in a mass spectrum. Mass spectral interpretation based on these ion compositions often provides tentative identifications when multiple library matches occur, when poor quality mass spectra are obtained, or when no library matches are found.
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Citation:Grange, A. H., P. Thomas, M. Solomon, and G. W. Sovocool. Identification of Compounds in South African Stream Samples Using Ion Composition Elucidation (Ice). Presented at 51st American Society for Mass Spectrometry Meeting, Montreal, CA, June 8-12, 2003.
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Contact: Chris Siebert - (702) 798-2234 or siebert.christopher@epa.gov
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Division: Environmental Sciences Division
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Branch: Environmental Chemistry Branch
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Product Type: Abstrct/Oral
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Presented: 06/08/2003
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Related Entries:
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Bullet Item Advances in Sampling, Separation, Detection and Identification That Address Unmet Needs of Oswer and the Regions
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Last Updated on Monday, October 22, 2007
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