Determinação de silício em material vegetal, pelo método colorimétrico do "azul-de-molibdênio"

Determination of silicon in plants by the molybdenum-blue colorimetric method

NOTA

Determinação de silício em material vegetal, pelo método colorimétrico do "azul-de-molibdênio"¹

Determination of silicon in plants by the molybdenum-blue colorimetric method

Pedro Roberto Furlani²; José Romano Gallo²

SUMMARY

Some aspects of the molybdenum-blue method of silicon determination in plants were studied. It was verified that the formation of the beta-isomer of the silicomolibdic acid, whose molar absorptivity is higher, depends on the solution acidity and the amount of reagent added. This isomer was obtained by adding 5 meq of H₂SO₄ and 2 ml of a 5% ammonium molibdate solution in a 50 ml calibrated flask. After reduction, the molibdenumblue formed was stabilized by adding 15 meq of H₂S0₄ more. The procedure also involves adding 1 ml of 10% oxalic acid solution, in order to eliminate phosphorus interference. The silicon solubilization, from 100 mg of dry material, was obtained by melting the ashes in nickel dishes with sodium hidroxide. This procedure proved suitable and accurate in the analysis of silicon in plants.

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Recebido para publicação em 7 de maio de 1977.

1

Pesquisa realizada com o auxílio do Banco Nacional de Desenvolvimento Econômico. Fundepro-42. Trabalho apresentado na XXV Reunião Anual da Sociedade Brasileira para o Progresso da Ciência, realizada no Rio de Janeiro — RJ, de 8 a 14 de julho de 1973.

2

Com bolsas de suplementação do C.N.Pq.

Datas de Publicação

• Publicação nesta coleção
  21 Dez 2007
• Data do Fascículo
  1978