The analysis was carried out in a Thermo TRACE GC Ultra
apparatus coupled to a Thermo ISQ mass detector, equipped with a
Thermo TriPlus autosampler. Gas chromatography was carried in a
Thermo Scienti fi c fused-silica capillary column TG-WAXMS A (30 m
long; 0.25 mm OD; 0.25 mm fi lm thickness). Chromatographic
conditions were as follows: 5 min at 40
C, 3
C/min up to 20 0
C,
15
C/min up to 240
C, 10 min at 240
C. Helium was used as carrier
gas at a fl ow rate of 1 mL/min, operating in split mode (ratio 30).
Total analysis time was 71 min. Detection was performed in the Full
Scan mode (dwell time 50 0 ms), with 70 eV ionization energy, and
source and quadrupole temperatures of 250
C. Detection was
stopped during the time interval for ethanol elution. Peak identi-fi cation was made by comparison of retention times and ion spectra
from real standards (SigmaeAldrich Química) and spectra from the
NIST mass spectral library. For each compound, including internal
standards, the sum of the areas of the peak s of up to fi ve charac-teristic ions was obtained. The relative abundance of a particular
compound was calculated as 10 0 0 times the addition of the areas of
the peaks of its characteristic ions divided by the addition of the
areas of the peak s of the characteristic ions of its selected internal
standard.