Figure 6.
Expanded 2.45–3.65 ppm regions of the 400 MHz 1H NMR spectra of (a) sunflower and (b) MRAFO oils heated according to a LSSFE at 180 °C for periods of 0–90 min. (samples were collected for 1H NMR analysis at the 0, 5, 10, 20, 30, 60 and 90 min. time-points). Abbreviations: 1, trans-9,10-epoxystearate-CHOHC- protons (δ = 2.63 ppm); 2, a combination of the -CHOHC- protons of 9,10-epoxy-octadecanoate, 9,10-epoxy-12-octadecenoate (leukotoxin), 12,13-epoxy-9-octadecenoate (isoleukotoxin) and cis-9,10-epoxystearate (δ = 2.86–2.93 ppm), although almost exclusively the latter LOP in spectrum (b); 3, 9,10-12,13-diepoxyoctadecanoate -CHOHC-CH2-CHOHC- functions (δ = 3.07 ppm); and 4, α-CH2 group of primary alcohol LOPs (δ = 3.62 ppm).