APPLICATION OF ONLINE COUPLED MASS-SPECTROMETRIC TECHNIQUES FOR THE STUDY OF ISOMERIC VITISPIRANES AND THEIR PRECURSORS OF GRAPEVINE CV RIESLING

On-line coupled multidimensional gas chromatography - mass spectrometf y (MDGC-MS) in the column combination -Wax/2,6-di-O-methyl-3-O-pentyl- beta-cyclo-dextrin allowed for the first time the determination of the enantiomeric composition of vitispiranes in Riesling wine. The order of elution was determined with the help of optically pure reference co mpounds. In the case of the (2R,5R)/(2S,5S)-enantiomers almost racemic proportions were determined, whereas in the case of the (2R,5S)/(2S,5 R)-enantiomers the (2S,SR)-isomer prevailed. On-line coupled liquid ch romatography - tandem mass spectrometry (LC-MS/MS) furthermore allowed the identification of the vitisprane-yielding precursor 3,4-dihydroxy -7,8-dihydro-beta-ionol 3-O-beta-D-glucopyranoside in Riesling wine an d grapevine leaves.