Absolute determination of soluble potassium in tea infusion by gamma-ray spectroscopy

Potassium content in tea brew was determined by gamma-ray spectroscopy, Using the 1461 keV gamma-ray fro M (40)K, the naturally occurring radioactive isotope of potassium. We measured radiation with a shielded HPGe detector from individual test samples of tea leaves, before and after infusion preparation, and from commercial instant tea powder. The correction factor for the gamma-ray self-absorption in the extended source was determined with the help of Monte-Carlo simulations. This gamma-ray spectroscopy technique enabled the absolute determination of potassium content with a relative uncertainty smaller than 4%, at the one standard deviation confidence level, showing the feasibility of this method. An experiment to evaluate a possible systematic Uncertainty due to K distribution heterogeneity in the sample was performed, with file result that the corresponding relative standard deviation is smaller than 2% at 95% confidence level. (C) 2009 Elsevier Ltd. All rights reserved.

CNPq (Conselho Nacional de Pesquisas, Brazil)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

FAPESP (Fundacao de Ainparo Pesquisa do Estado de Sao Paulo, Brazil)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

CAPES (Coordenacao de Aperfeicoamento de Pessoal de Ensino Superior, Brazil)