5
d 4 - reveratrol as internal standard, synthesized “ad hoc” by a simple coupling reaction starting from synthons properly prepared (Fig. 1.4).
The purpose of the authors was to assay the amount of resveratrol in red wine in
a triple quadrupole instrument working in SRM mode. Surprisingly, the authors
realized that d 4 -reveratrol could not be used in the analysis because of an unusual
gas-phase fragmentation behavior of the internal standard respect to d 0 -reveratrol
(Fig. 1.5).
The fragmentation pattern of labelled resveratrol was ascribed to hydrogens hopping through the carbon skeleton of the highly conjugated resveratrol molecular ion
prior the fragmentation. This is obviously not visible in the MS/MS spectrum of
d 0 -reveratrol, while it became evident when deuteria are placed on one of the two
rings. The problem can be overcome by using a different type of internal standard,
i.e. resveratrol enriched by
13
C on the carbon backbone as reported recently for the
determination of resveratrol by PS-MS/MS [15].
Fig. 1.3 Fragmentation of oleuropein
1 Evaluation of Quality and Safety of Foods by Tandem Mass Spectrometry