<p xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mml="http://www.w3.org/1998/Math/MathML"><bold>Gas chromatography-mass spectrometry</bold>. Samples were analyzed by gas chromatography using a HP6890 instrument coupled with a HP 5973 mass spectrometer. The gas chromatograph is equipped with a split-splitless injector and a Factor FourTM VF-35ms 5% fenil-methylpolysiloxane, 30 m, 0.25 mm, 0.25 &#956;m film thickness capillary column. Gas chromatography conditions include a temperature range of 50 to 250&#176;C at 40&#176;C/min, with a solvent delay of 5 min. The injector was maintained at a temperature of 250&#176;C. The inert gas was helium at a flow of 1.0 mL/min, and the injected volume in the splitless mode was 1 &#956;L. The MS conditions were the following: ionization energy, 70 eV; quadrupole temperature, 100&#176;C; scanning velocity, 1.6 scan/s; weight range, 40-500 amu.</p>