Distinguishing monosaccharide stereo- and structural isomers with TOF-SIMS and multivariate statistical analysis.
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is utilized to examine the mass spectra and fragmentation patterns of seven isomeric monosaccharides. Multivariate statistical analysis techniques, including principal component analysis (PCA), allow discrimination of the extremely similar mass spectra of stereoisomers. Furthermore, PCA identifies those fragment peaks that vary significantly between spectra. Heavy isotope studies confirm that these peaks are indeed sugar fragments, allow identification of the fragments, and provide clues to the fragmentation pathways. Excellent reproducibility is shown by multiple experiments performed over time and on separate samples. This study demonstrates the combined selectivity and discrimination power of TOF-SIMS and PCA and suggests new applications of the technique including differentiation of subtle chemical changes in biological samples that may provide insights into cellular processes, disease progress, and disease diagnosis.
Berman
Elena S F
ES
Biosciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA. berman2@llnl.gov
Kulp
Kristen S
KS
Knize
Mark G
MG
Wu
Ligang
L
Nelson
Erik J
EJ
Nelson
David O
DO
Wu
Kuang Jen
KJ
D013058:Mass Spectrometry / Q000379:methods*; D009005:Monosaccharides / Q000737:chemistry*; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D013237:Stereoisomerism
D009005:Monosaccharides