1. Group of Spectrometry, Sample Preparation and Mechanization (GEPAM), Institute of Chemistry University of Campinas, UNICAMP PO Box 6154 13084‐862 Campinas SP Brazil
2. National Institute of Science and Technology for Bioanalytics, Institute of Chemistry University of Campinas, UNICAMP 13084‐862 Campinas SP Brazil
3. Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias Universidade Estadual Paulista “Júlio de Mesquita Filho” Jaboticabal SP Brazil