DTIMS Time-of-Flight Mass Spectrometry

FIGURE 9.8 First ambient pressure ion mobility-mass spectrometer. (From Karasek, Kim,and Hill, Mass identified mobility specfi-a of p-nitrophenol and reactant ions in plasma chromatography, Anal. Ghent. 1976, 48(8), 1133-1137. With permission.) 

Reaction Region Drift Region Segmented Segmented Q1 Q2 MCP Detector 

FIGURE 9.9 (a) Schematic diagram of glass tube ion mobility spectrometer interfaced to a 

FIGURE 9.10 Two-dimensional direct infusion ESI ion mobility MS spectrum of E. coli culture producing over 1,000 metabolite peaks. (Reprinted fromDwivedi et al.. Metabolic profiling by ion mobility-mass spectrometry (IMMS), Metabolomics 2007, 21, 1115-1122. With permission.) 

Other ions in the spectrum are the result of ion fragmentation at the IMS-MS interface. The ion fragments are easy to recognize in the spectrum because they produce a mass spectrum at a single mobility. Within the metabolite trend band, individual metabolite ions are positioned above or below the average trend line as a result of differences in their SCS (0/m). Thus, isomers and isobars are separated within the metabolite trend band. Hundreds of specific metabolites can be identified and quantified from a single ion mobility MS run in a matter of seconds. 

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