Analyses were performed on a Hewlett-Packard 5890
gas chromatograph (Agilent Technologies Mexico, Mexico
City) equipped with a flame ionization detector (FID)
operated at 290 C. The injection liner was a packed liner,
with internal diameter of 4 mm, for a volume of 800 lL
(Hewlett-Packard 18740–60840, Agilent Technologies
Mexico, Mexico City). Samples (1.6 lL) were loaded into
the injection port at 290 C as split injections at a ratio
of 1:100 with a 10-mL syringe (Hamilton). The column
used was an Ultra 2 (crosslinked 5% Ph Me silicone;
25 m 0.32 mm 0.52 lm film thickness, Agilent Technologies
Mexico, Mexico City). The column temperature
program was as follows: 180 C for 2 min, 15 C/min to
reach 280 C for 6.7 min, 280 C for 15 min (23.7 min
total). The carrier gas was N2 with a flow rate of 1.0 mL/
min at 290 C and a septum purge of 2 mL/min