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174 Nuclear Science and Technology | Progress Report

Fig 23. Bottles of the bovine kidney reference material.

All the steps for the production of a bovine showed that the mussel candidate reference
kidney reference material were developed, material presents particle size distribution sim-
including sampling, sample pretreatments, ilar to the IAEA-407 fish homogenate, prepared
freeze-drying, grinding, sieving, homogeniza- with similar technique (Fig. 24). (Partnership:
tion and gamma ray sterilization (Fig. 23). Phys- CQMA – IPEN; Funding: IAEA, FAPESP, CNPq,
ical and chemical characterization following CNEN, CAPES).
internationally agreed recommendations were
performed, with emphasis on the assessment NAA studies in Crassostrea oyster shells
of the stability of the material, its homogeneity
status, residual water content and granulomet- In this study, the neutron activation is used in
ric characterization. An international interlabo-
ratory program was performed for assignment
of As, Cd, Cu, Cl, Co, Cr, Fe, Hg, K, Mg, Mn, Na,
Pb, Se and Zn values and associated expanded
uncertainties for the kidney tissue.

In the case of the previously prepared mussel
reference material, its particle size distribution
was characterized by Laser Diffraction Particle Fig 24. Particle size distribution for various reference materials.
Analysis and compared with other reference
materials as the distribution may interfere with
the homogeneity properties of the material. It the Crassostrea genus oyster shells (Fig. 25) to
was observed that the mussel candidate refer- verify the feasibility of using trace elements
ence material presents mean particle size of as paleo-environmental markers. Samples of
94.6 ± 0.8 μm, with Gaussian distribution. The oyster shells were collected covering the South,
comparison with the results obtained for cer- Southeast and Northeast regions of Brazil.
tified reference materials with similar matrix To determine the crystalline structure of the

Instituto de Pesquisas Energéticas e Nucleares