THE POTENTIAL OF PYROLYSIS-(METHYLATION) GAS-CHROMATOGRAPHY MASS-SPECTROMETRY IN THE ANALYSIS OF WINE POLYPHENOLICS

The phenolic compounds of a red Italian wine were separated by column chromatography into three fractions: (a) monomers, (b) red polymers and (c) yellow and brown polymers (tannins). Polymers were subjected to pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) using a heated-filament pyrolyzer coupled to a capillary gas chromatograph and an ion-trap-detector mass spectrometer. Samples were pyrolysed as such or mixed with an aqueous solution of tetramethylammonium hydroxide in order to perform a simultaneous pyrolysis-methylation (SPM). Pyrograms showing diagnostic markers for flavonoids and phenolic acids are reported. Advantages and limitations of both PY/GC/MS and SPM/GC/MS are discussed.