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APLICAÇÃO DA IRRADIAÇÃO CURTA NA ANÁLISE POR ATIVAÇÃO COM NÊUTRONS DE AMOSTRAS DE MEXILHÃO

ABSTRACT RESUMO Análises de elementos traço em amostras de mexilhão apresentam grande interesse para o uso na monitoração da região costeira. Este trabalho apresenta os resultados preliminares da determinação dos elementos Br, Cl, K, Mg, Mn e Na obtidos nas amostras de mexilhão Perna perna por meio de irradiação curta da análise por ativação com nêutrons (NAA). Amostras de mexilhões coletadas na região costeira do litoral paulista foram limpas, trituradas, homogeneizadas e secas por meio da liofilização para posteriores análises. Alíquotas das amostras obtidas na forma de pó foram pesadas em invólucros de polietileno e irradiadas no reator nuclear IEA – R1 juntamente com padrões sintéticos de elementos. O tempo de irradiação foi de 10 min e sob fluxo de nêutrons térmicos de 9,6 x 10 9 n cm -2 s -1 . As medições das atividades gama das amostras e dos padrões sintéticos foram feitas utilizando um detector de Ge hiperpuro ligado a um espectrômetro de raios gama. As concentrações dos elementos acima citados foram calculadas pelo método comparativo. Concentrações dos elementos Br e Mn foram obtidas aos níveis de mg kg -1 e de Cl, K, Mg e Na da ordem de percentagens foram determinadas nos mexilhões. Os resultados obtidos no material de referência NIST 1566b Oyster Tissue indicaram uma boa concordância com os valores certificados.

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Jun 1, 2014