1. EMBRAPA Instrumentation, 1452
XV de Novembro Street, São Carlos, São Paulo 13560-970, Brazil
2. Department
of Chemistry, Federal University of São Carlos, Hwy. Washington
Luiz, km 235, São Carlos, São Paulo 13565-905, Brazil
3. University of Maryland, College Park, Maryland 20742, United States
4. USDA-ARS, Sustainable Agricultural Systems Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, 10300 Baltimore Ave., Beltsville, Maryland 20705, United States