title: Fragmentation patterns of methyloxime-trimethylsilyl derivatives of constitutive mono- and disaccharide isomers analyzed by gas chromatography/field ionization mass spectrometry.
abstract: BACKGROUND
  In saccharide analysis by gas chromatography/mass spectrometry (GC/MS), electron ionization (EI) is used almost exclusively, whereas other gentler methods of ionization are rarely used. Field ionization (FI) is recognized as a GC/MS ionization method that causes fewer fragment ions, but only few studies are available on its use in saccharide analysis.
  
  
  METHODS
  To evaluate the usefulness of FI in profiling isomeric saccharides by GC/MS and to explore its potential application in metabolome analysis, we compared EI, chemical ionization (CI), and FI spectral patterns of consecutive mono- and disaccharides derivatized with methoxamine-HCl and N-methyl-N-(trimethylsilyl)trifluoroacetamide.
  
  
  RESULTS
  FI produced molecular ions and fragment ions characteristic of constitutive isomeric disaccharides. All of the derivatized saccharides that originally had free anomeric OH showed methyloxime-moiety fragment ions, attributable to the cleavage between C2 and C3. Some fragment ions in FI were indicative of the position of dihexose linkages. Although EI with lowered voltage (18 V, 130 °C) produced fewer fragment ions than conventional EI (70 V, 250 °C) did, fragmentation patterns were different from those of FI.
  
  
  CONCLUSIONS
  Our data show that FI is useful for distinguishing isomeric saccharides in qualitative analyses.
authors.affiliation: University of Vienna, Department of Molecular System Biology, Althanstrasse 14, A-1090, Vienna, Austria.|Metabolome Systems Research Team, RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro, Tsurumi, Yokohama City, Kanagawa, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Furuhashi
authors.affiliation: JEOL Ltd., 1-2 Musashino 3-chome Akishima, Tokyo, 196-8558, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ishii
authors.affiliation: JEOL Ltd., 1-2 Musashino 3-chome Akishima, Tokyo, 196-8558, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: University of Vienna, Department of Molecular System Biology, Althanstrasse 14, A-1090, Vienna, Austria.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Weckwerth
authors.affiliation: Collaboration Promotion Unit, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama, Japan.
authors.forename: Takemichi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D004187:Disaccharides / Q000737:chemistry*; D005463:Fluoroacetates / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D007536:Isomerism; D009005:Monosaccharides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D014297:Trimethylsilyl Compounds / Q000737:chemistry*
chemical_list: D000081:Acetamides; D004187:Disaccharides; D005463:Fluoroacetates; D009005:Monosaccharides; D014297:Trimethylsilyl Compounds; C086665:N-methyl-N-(trimethylsilyl)trifluoroacetamide