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Figure 2.16. EESI-QTOF mass spectra of grapes at different maturity stages, showing differentiation
patterns: (a) overripe grapes; (b) normally ripe grapes; and (c) unripe grapes Ref. [135], Figure 5, p. 1452.
Reproduced with permission of American Chemical Society.
grapes, or strawberries contained signals of both volatile and nonvolatile compounds
in the mass region m / z 100
1000. Clear differences between mass spectra obtained by
analysis of samples at various ripening stages were observed, as demonstrated in
Figure 2.16 for grapes. Due to the complexity of the records, multivariate statistical
analysis employing principal component analysis was used for further visualization.
DESI-MS was used by Jackson et al. to directly characterize constituents of dietary
supplements containing Stevia leaf extracts [133]. Among other constituents, such as
oligosaccharides and polysaccharides, characteristic diterpene glycosides, which are
responsible for sweet taste, were detected. The compliance of commercial products
with declared composition could be con
-
rmed this way.
Vaclavik et al. used DART-MS for authenticity assessment of extra virgin olive oil
based on statistical analysis of data representing pro
les of triacylglycerols and some
phenolic compounds [127]. In addition to differentiation of various olive oil grades,
detection of adulteration by hazelnut oil at levels as low as 6% (v/v) was demon-
strated. High-throughput analysis was achieved due to simple sample preparation
and automated sample introduction in front of a DART ion source. The extraction of
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