1. ThoMSon Mass Spectrometry Laboratory, Institute of Chemistry; University of Campinas; UNICAMP 13083-970; Campinas; SP; Brazil
2. Waters Limited; Atlas Park; Simonsway Manchester; M22, 5PP; UK
3. National Institute of Metrology, INMETRO; Division of Chemical Metrology 25250-020; Duque de Caxias; RJ; Brazil