GFAAS Determination of Zinc in Fish Feed and Feces Using Slurry Sampling
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GFAAS Determination of Zinc in Fish Feed and Feces Using Slurry Sampling Mayra Anton Dib Saleh & Renato de Cássio Ferreira Neves & Fábio Arlindo Silva & Paula Martin de Moraes & Vanessa Rosa Loureiro & Paulo dos Santos Roldan & Pedro de Magalhães Padilha
Received: 15 May 2008 / Accepted: 15 September 2008 / Published online: 7 October 2008 # Springer Science + Business Media, LLC 2008
Abstract This paper presents a simple, fast, and sensitive method to determine zinc in samples of feces and fish feed by electrothermal atomic absorption spectrometry through the direct introduction of slurries of the samples into the spectrometer’s graphite tube. The procedure is based on the injection of 10 μL of an acidified aqueous solution containing 0.50% w/v of feces or feed and 0.50% v/v HNO3 into graphite tube. The limits of detection and quantification calculated for 20 readings of the blank of the standard slurries (0.50% w/v of feces or feed devoid of zinc) were 0.04 and 0.13 μg L−1 for the standard feces slurries and 0.05 and 0.17 μg L−1 for the standard feed slurries. The proposed method was applied in studies of digestibility of zinc in different fish feeds, and their results proved compatible with that obtained from samples mineralized by acid digestion using microwave oven. Keywords AAS . Sampling . Process Analysis . Biological Samples . Fish Nutrition M. A. D. Saleh : R. de Cássio Ferreira Neves : F. A. Silva Programa de Pós-Graduação em Zootecnia, Faculdade de Medicina Veterinária e Zootecnia, UNESP, Caixa Postal 560, 18618-000 Botucatu, SP, Brazil M. A. D. Saleh (*) : P. M. de Moraes : V. R. Loureiro : P. de Magalhães Padilha Departamento de Química e Bioquímica, Instituto de Biociências, UNESP, Caixa Postal 510, 18618-000 Botucatu, SP, Brazil e-mail: [email protected] P. dos Santos Roldan Instituto de Química e Biotecnologia, Universidade Federal de Alagoas, 57072-970 Maceió, AL, Brasil
Introduction Zinc is a trace element whose role is essential in many biochemical processes. It is a component of hundreds of proteins involved in intermediary metabolism, hormone secretion pathway, and immune defense, and Zn enzymes participate in the synthesis and decomposition of proteins, fats, carbohydrates, and nucleic acids (McDowell 1992; Solomons 1992). The presence of this element in the cells is processed by protein carriers and in storage processes through metallothionein. A change in the concentration of this element in tissues can be observed in many pathological processes (Mertz 1987; McCall et al. 2000). Because zinc participates in the metabolism of numerous enzymes, it is an essential element required for normal growth and is indispensable in animal diets (Christianson and Cox 1999; Yamaguchi 1998; Scarpa and Gatlin 1992). Thus, artificial diets for animals should contain the concentration of zinc required by the animal’s metabolism to maintain its health and high weight gain rates (Shearer et al. 1992). However, essential elements should also be in an available form for use by the organism (O’Dell 1984). An
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