Desenvolvimento de procedimentos para o preparo de amostra na determinação de macro e micronutrientes em plantas oleaginosas por espectrometria de absorção atômica

Abstract

The efficiency of sample preparation procedures employing wet and dry digestion was evaluated in multielement determination of Cu, Fe, Mn, Zn, Ca and Mg in oilseeds species by flame atomic absorption spectrometry. Procedures based on acid digestion were evaluated using thermal energy (open system using a heating block and closed system heating in an oven at 150 oC), decomposition by dry heat in an open system procedure employing a muffle furnace and extraction with ultrasonic energy (ultrasonic bath) using dilute acids. The accuracy and precision of the procedures were evaluated by analysis of two reference materials of the Empresa Brasilera de Pesquisa Agropecuária (Embrapa Agropecuária Oeste Dourados, MS) and also by recovery tests, and the results were in agreement at 95% of confidence level. The concentration ranges for nutrients were: 5.27 ± 0.24 - 17.09 ± 0.93 μg g-1 Cu, 71.32 ± 4.74 - 343.19 ± 38.38 μg g-1 Fe, 20.12 ± 1.02 - 49.08 ± 0.49 μg g-1 Mn, 32.45 ± 1.86 - 43.51 ± 4.27 μg g-1 Zn, 1.13 ± 0,01 - 3.86 ± 0.13 mg g-1 Ca and 2.07 ± 0.18 - 3.14 ± 0.06 mg g-1 Mg (dry matter). The content obtained for Cu, Fe, Mn, Zn, Ca and Mg by the proposed procedures were compared by Student test-t and the results showed agreement at 95% confidence for most of elements.