Identification of Uncommon Plant Metabolites Based on Calculation of Elemental Compositions Using Gas Chromatography and Quadrupole Mass Spectrometry

摘要

Unknown compounds in polar fractions of Arabidopsia thaliana crude leaf extracts were identified on the basis of calculations of elemental compositions obtained from gas chromatography/low-resolution quadnipole mass spec-trometric data. Plant metabolites were methoximated and silylated prior to analysis. All known peaks were used as internal references to construct polynomial recalibration curves of from raw mass spectrometric data. Mass ac-curacies of 0.005 ± 0.003 amu and isotope ratio errors of 0.5 ± 0.3% (A + 1/A), respectively, 0.3 ± 0.2% (A + 2/A), could be achieved. Both masses and isotope ratios were combined when the elemental compositions of unknown peaks were calculated. After calculation, com-pound identities were elucidated by searching metabolic databases, interpreting spectra, and, finally, by compari-son with reference compounds. Sum formulas of more than 70 peaks were determined throughout single GC/ MS chromatograms. Exact masses were confirmed by high-resolution mass spectrometric data. More than 15 uncommon plant metabolites were identified, some of which are novel in Arabidopsis, such as tartronate semi-aldehyde, citramalic acid, allothreonine, or glycolic amide.