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| Souza,N.K.P.; Detmann,E.; Pina,D.S.; Valadares Filho,S.C.; Sampaio,C.B.; Queiroz,A.C.; Veloso,C.M.. |
| The objective of this work was to evaluate combinations between acid digestion techniques and spectrophotometric quantification to measure chromium concentration in cattle feces. Digestion techniques were evaluated based on the use of nitric and perchloric acids, sulfuric and perchloric acids, and phosphoric acid. The chromium quantification in the solutions was performed by colorimetry and by atomic absorption spectrophotometry (AAS). When AAS was used, the addition of calcium chloride to the solutions as a releasing agent was also evaluated. Several standard samples containing known chromium contents were produced (0, 2, 4, 6, 8 and 10g of chromium per kg of feces) using cattle feces obtained from three different animals to evaluate the accuracy of the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Atomic absorption; Colorimetry; External markers; Chromic oxide. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-09352013000500028 |
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| Souza,N.K.P.; Detmann,E.; Valadares Filho,S.C.; Costa,V.A.C.; Pina,D.S.; Gomes,D.I.; Queiroz,A.C.; Mantovani,H.C.. |
| The accuracy of two different methods in measuring the ammonia nitrogen (N-NH3) concentration in rumen fluid were evaluated: a catalyzed indophenol colorimetric reaction (CICR) and the Kjeldahl distillation (KD). Five buffered standard solutions containing volatile fatty acids, true protein, and known ammonia concentrations (0, 3, 6, 12, and 24 N-NH3 mg/dL) were used to simulate rumen fluid. Different ratios (10:1, 7.5:1, 5:1, 2.5:1, 1:1, 1:2.5, 1:5, 1:7.5, and 1:10) of a potassium hydroxide solution (KOH, 2 mol/L) to standard solutions were evaluated by the KD method. The accuracy of each method was evaluated by adjusting a simple linear regression model of the estimated N-NH3 concentrations on the N-NH3 concentrations in the standard solutions. When the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ammonia nitrogen; Indophenol colorimetric reaction; Kjeldahl distillation. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-09352013000600024 |
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