Figure 3.

Detailed part of the two-dimensional contour plot (Figure 1) to demonstrate the result of a successful feeding experiment after administration of the stable isotope-labeled precursor [6,6,6-²H₃]-(±)-mevalonolactone (d₃-MVL) to isolated exocarp of grape berries (Lemberger cultivar). The regions labeled with the numbers 10, 3 and 5 correspond to the genuine sesquiterpene hydrocarbons as defined in Table 1. 10a (d₈), 3a (d₉) and 5a (d₈) are the isotopologues with the highest, possible incorporation of deuterium when d₃-MVL is used as precursor (the maximum possible number of deuterium atoms incorporated is given in brackets). The 3D view of the chromatogram section shown can be found in Supporting Information File 1.