Figure 2.
Hexane extracts of leaves from field-grown plants. (A) Hexane extracts from pooled leaf samples of field-grown plants for a qualitative assessment of green leaf volatile (GLV) pools, analyzed by GC-MS with a split ratio of 1/100 onto a nonpolar column; only (E)-hex-2-enal was identified due to poor resolution of (E)-hex-2-enal and (Z)-hex-3-en-1-ol on the nonpolar column; no ester peaks were detected. For raw data, see F3A_SchumanBarthelBaldwin2012chromatograms.xlsx (Dryad: Schuman et al., 2012). (B) Example chromatograms from hexane extracts of individual leaf samples from field-grown plants, analyzed by GC-FID on a wax column. The dominant compound was (E)-hex-2-enal; (Z)-hex-3-en-1-ol was also present in quantifiable amounts. (Z)-3-hexenyl acetate was chosen as an internal standard because no esters were detectable in the preliminary qualitative GC-MS analysis (1A), and because its chemical similarity to (E)-hex-2-enal and (Z)-hex-3-en-1-ol made it a good choice of internal standard for normalization and calculation of yield from extracts. For raw data, see F3B_SchumanBarthelBaldwin2012chromatograms.xlsx (Dryad: Schuman et al., 2012). IS: internal standard.