MARINA BEATRIZ AGOSTINI VASCONCELLOS

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  • Artigo IPEN-doc 25791
    Micro-homogeneity evaluation of a bovine kidney candidate reference material
    2019 - CASTRO, L.; MOREIRA, E.G.; VASCONCELLOS, M.B.A.
    The minimum sample intake for which a reference material remains homogeneous is one of the parameters that must be estimated in the homogeneity assessment study of reference materials. In this work, Instrumental Neutron Activation Analysis was used to evaluate this quantity in a bovine kidney candidate reference material. The mass fractions of 9 inorganic constituents were determined in subsamples between 1 and 2 mg in order to estimate the relative homogeneity factor (HE) and the minimum sample mass to achieve 5% and 10% precision on a 95% confidence level. Results ob-tained for HE in all the analyzed elements were satisfactory. The estimated minimum sample intake was between 2 mg and 40 mg, depending on the element.
  • Artigo IPEN-doc 25077
    Stability assessment of a bovine kidney reference-material candidate
    2018 - CASTRO, LILIANA; MOREIRA, EDSON G.; VASCONCELLOS, MARINA B.A.; LANGE, CAMILA N.; PEDRON, TATIANA; BATISTA, BRUNO L.
    Reference materials are used worldwide and necessary for quality control purposes during analytical determinations. The present study describes the stability evaluation of a bovine kidney reference-material candidate. An isochronous layout was performed, in which the flasks involved are exposed at different temperatures for different time periods and then are analyzed at the same time at the end of the study. The mass fractions of ten inorganic constituents were determined using instrumental neutron activation analysis and inductively coupled plasma mass spectrometry. Statistical analysis, univariate and multivariate, showed no significant differences in composition between units exposed to the different temperatures and times. The reference material may be transported under normal transportation conditions and the certified values and uncertainties will continue to be valid for a period of 2 years.