Revista Brasileira de Ciência do Solo
On-line version ISSN 1806-9657
COSTA, Leonardo Alves da and MENEZES, Maria Ângela de Barros Correia. Determination of manganese in the presence of iron: soil analysis by instrumental neutron activation. Rev. Bras. Ciênc. Solo [online]. 2012, vol.36, n.3, pp.775-786. ISSN 1806-9657. http://dx.doi.org/10.1590/S0100-06832012000300009.
The nuclear analytical technique of neutron activation is a multielemental, accurate and precise technique. Aside from other characteristics, the method is particularly suitable for element determination, mainly in soil. However, in the case of irradiation, samples can be influenced by primary nuclear interferences. The contribution of these interferences depends on the characteristics of the neutron flux, irradiation site, etc. These reactions occur during irradiation, when the sample is exposed to the neutron flux in the reactor with contribution of neutrons with different energies. The interference can be significant when determining Mn in the presence of Fe, due to the extra production of 56Mn that can make it difficult to affirm whether the Mn concentration determined was due to Fe interference or not. The purpose of this study was to verify whether this interference is significant in the analysis of Fe-rich samples in the TRIGA MARK I IPR-R1 reactor of the CDTN, a center for nuclear technology development of the Comissão Nacional de Energia Nuclear - CNEN. Soil samples from Quadrilátero Ferrífero, Minas Gerais, Brazil, with Fe concentrations from 40 to 60 % were analyzed by determining Mn. Results indicated that the production of 56Mn by the reaction of 56Fe with fast neutrons is not significant, so no correction factor had to be applied to correct the interference.
Keywords : soil; Iron Quadrangle; nuclear interference.