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AUTOMATED DETERMINATION OF PRECURSOR ION, PRODUCT ION, AND NEUTRAL LOSS COMPOSITIONS AND DECONVOLUTION OF COMPOSITE MASS SPECTRA USING ION CORRELATION BASED ON EXACT MASSES AND RELATIVE ISOTOPIC ABUNDANCES
Citation:
GRANGE, A. H. AND G. SOVOCOOL. AUTOMATED DETERMINATION OF PRECURSOR ION, PRODUCT ION, AND NEUTRAL LOSS COMPOSITIONS AND DECONVOLUTION OF COMPOSITE MASS SPECTRA USING ION CORRELATION BASED ON EXACT MASSES AND RELATIVE ISOTOPIC ABUNDANCES. RAPID COMMUNICATIONS IN MASS SPECTROMETRY. John Wiley & Sons, Ltd., Indianapolis, IN, 22:2375-2390, (2008).
Impact/Purpose:
Identifying contaminants is the first step in assessing human health and ecological risks posed by contaminated sites. Thorough and rapid characterization of accidental, deliberate, or weather-related, dispersive events requires fast analyses and a high throughput. To meet this need, an autosampler/Direct Analysis in Real Time (DART®) ion source/Time-of-Flight Mass Spectrometer (TOFMS) that could be transported to dispersion events within a van and a wipe sample transport and collection device are under development.
Description:
After a dispersive event, rapid determination of elemental compositions of ions in mass spectra is essential for tentatively identifying compounds. A Direct Analysis in Real Time (DART)® ion source interfaced to a JEOL AccuTOF® mass spectrometer provided exact masses accurate to within 2 mDa for most ions in full scan mass spectra and relative isotopic abundances (RIAs) accurate to within 15-20% for abundant isotopic ions. To speed determination of the correct composition for precursor ions and most product ions and neutral losses, a three-part software suite was developed. Starting with text files of m/z ratios and their mass peak areas from mass spectra acquired at low, moderate, and high collision energies, the Ion Extraction Program (IEP) compiled lists for the most abundant monoisotopic ions of their exact masses and the RIAs of the +1 and +2 isotopic peaks when area thresholds were met; precursor ions; and higher-mass, precursor-related ions. The Ion Correlation Program (ICP) determined if a precursor ion composition could yield a product ion and corresponding neutral loss compositions for each product ion in turn. The Input and Output Program (IOP) provided the ICP with each precursor ion:product ion pair for multiple sets of error limits and prepared correlation lists for single or multiple precursor ions. The software determined the correct precursor ion compositions for 21 individual standards and for three- and seven-component mixtures. Partial deconvolution of composite mass spectra was achieved based on exact masses and RIAs, rather than on chromatography.