The volatile compounds were identified by comparing their mass
spectra (m/z values of the most important ions) with spectral data
from the National Institute of Standards and Technology 2002 library
as well as retention indices published in the literature (http://
pherobase.com). Relative retention indices were determined by injection
into the column of a solution containing the homogenous series
of normal alkanes (C7–C30; by Sigma-Aldrich) in the same temperature
programmed run, as described above. Quantification of selected compounds
was carried out using external calibration curves.