6
1.2.3 Determination of Phenylethanoids in Extra Virgin
Olive Oil
Sometimes it may be challenging to develop a method based on isotope standard
dilution analysis, simply because of the lack of commercial suitable isotopic standards and/or because their synthesis is very tedious, if not impossible. This is the
case of the determination of hydroxytyrosol and tyrosol derivatives in extra virgin
olive oil [16]. According to a recent international regulation [17], these compounds
may be considered molecular quality markers which increase the value added of the
oil. The regulation states, in fact, that the presence of these compounds, above the
concentration threshold of 5 mg per 20 g, allows the producer to report on the main
label of the food a sentence which summarizes the health effect concerning its antioxidant effects. The family of this phenols comprises the free alcohols tyrosol and
hydroxytyrosol, and their ester dialdehydic derivatives; although it is quite easy to
synthesize the deuterated analogues of the free alcohols, the structural complexity
of the esters makes difficult to obtain stable isotopomers. Bartella et al. [16] proposed the MS/MS analysis of the simple tyrosol and hydroxytyrosol using the
homologue deuterated compounds as internal standards, after a simple and fast
hydrolytic step. The method relies on a two-steps analysis performed on the polar
extract of extra virgin olive oil (Fig. 1.6): in the first step the extract is analyzed “as
is” in the presence of the internal standards using an electrospray triple quadrupole
Fig. 1.4 Synthesis of d 4 -reveratrol
G. Sindona and L. Di Donna
1.2.3 Determination of Phenylethanoids in Extra Virgin
Olive Oil
Sometimes it may be challenging to develop a method based on isotope standard
dilution analysis, simply because of the lack of commercial suitable isotopic standards and/or because their synthesis is very tedious, if not impossible. This is the
case of the determination of hydroxytyrosol and tyrosol derivatives in extra virgin
olive oil [16]. According to a recent international regulation [17], these compounds
may be considered molecular quality markers which increase the value added of the
oil. The regulation states, in fact, that the presence of these compounds, above the
concentration threshold of 5 mg per 20 g, allows the producer to report on the main
label of the food a sentence which summarizes the health effect concerning its antioxidant effects. The family of this phenols comprises the free alcohols tyrosol and
hydroxytyrosol, and their ester dialdehydic derivatives; although it is quite easy to
synthesize the deuterated analogues of the free alcohols, the structural complexity
of the esters makes difficult to obtain stable isotopomers. Bartella et al. [16] proposed the MS/MS analysis of the simple tyrosol and hydroxytyrosol using the
homologue deuterated compounds as internal standards, after a simple and fast
hydrolytic step. The method relies on a two-steps analysis performed on the polar
extract of extra virgin olive oil (Fig. 1.6): in the first step the extract is analyzed “as
is” in the presence of the internal standards using an electrospray triple quadrupole
Fig. 1.4 Synthesis of d 4 -reveratrol
G. Sindona and L. Di Donna