title: A fast and simple methodology for determination of yttrium as an inert marker in digestibility studies.
abstract: The need to develop a fast, simple and low cost methodology for the determination of yttrium in fish diets and faeces using a microwave digestion system and atomic absorption spectrometry with flame atomization analysis was the main aim of this study. The final methodology consisted in the digestion of approximately 300mg of dry fish diet or 100mg of dry fish faeces in teflon vessels using Parr reactor bombs, at high pressure, in a domestic microwave system with nitric acid solution. After digestion, 330μl of a 120mg potassium nitrate/ml solution was added to each solution. Yttrium was determined using a calibration with aqueous standards. Analytical difficulties and problems encountered during the optimizations were overcome and the application of the final methodology to the fish diets and faeces samples was carried out with suitable results.
authors.affiliation: Laboratório de Química, CIMAR/CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal. Electronic address: pedroareis@ciimar.up.pt.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Reis
authors.affiliation: Laboratory of Nutrition, Growth and Quality, CIMAR/CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal.
authors.forename: Luísa M P
authors.initials: LM
authors.lastname: Valente
authors.affiliation: Laboratório de Química, CIMAR/CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal.
authors.forename: C Marisa R
authors.initials: CM
authors.lastname: Almeida
keywords: Atomic absorption spectrometry; Digestibility studies; Fish diets; Fish faeces; Inert marker; Microwave digestion; Yttrium