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  • 1 Universidade de São Paulo Centro de Energia Nuclear na Agricultura P.O. Box 96 13400-970 Piracicaba, SP Brazil
  • 2 Delft University of Technology Reactor Institute Delft Mekelweg 15 2629JB Delft The Netherlands
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Abstract  

The degree of homogeneity is normally assessed by the variability of the results of independent analyses of several (e.g., 15) normal-scale replicates. Large sample instrumental neutron activation analysis (LS-INAA) with a collimated Ge detector allows inspecting the degree of homogeneity of the initial batch material, using a kilogram-size sample. The test is based on the spatial distributions of induced radioactivity. Such test was applied to samples of Brazilian whole (green) coffee beans (Coffea arabica and Coffea canephora) of approximately 1 kg in the frame of development of a coffee reference material. Results indicated that the material do not contain significant element composition inhomogeneities between batches of approximately 30–50 g, masses typically forming the starting base of a reference material.