1. ThoMSon Mass Spectrometry Laboratory, Institute of Chemistry; University of Campinas - UNICAMP; Campinas 13083-970 SP Brazil
2. Fats and Oils Laboratory, Faculty of Food Engineering; University of Campinas - UNICAMP; Campinas 13083-970 SP Brazil
3. Department of Fundamental Chemistry; Federal University of Pernambuco; Recife 50740-560 PE Brazil