Determinação fotométrica do ácido ascórbico

  • Jorge Leme Junior Escola Superior de Agricultura Luiz de Queiroz
  • E. Malavolta Escola Superior de Agricultura Luiz de Queiroz

Resumo

The photometric determination of ascorbic acid with the "E. E. L. portable colorimeter" can be carried" out rapid and conveniently using either 3% HPO3 or 0,4% (COOH) 2 as protective agent. The standards would contain from 2 to 20 micrograms of ascorbic acid per ml of metaphosphoric or oxalic acid solutions. We mix 10 ml of these solutions with 3 ml of the adequate citrate buffer solutions, and we pipet 5 ml of the resulting mixture to a matched test tube containing 5 ml of sodium - 2,6 - dichlorobenzenoneindophenol (80 mg per liter); then we shake well and after 15 seconds the extintion is read using green filter. The readings are subtracted from the blank one. Designating the differences by x and the concentrations of ascorbic acid/ml in the standards by y, we get, with the acid of the method of least squares, the following regression equations: for the metaphosphoric acid Y = 0,543x + 0,629 for the oxalic acid Y = 0,516x + 0,422, which permit, by interpolating, the determination of the ascorbic acid content in plant materials.

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Publicado
1949-12-30
Como Citar
Leme Junior, J., & Malavolta, E. (1949). Determinação fotométrica do ácido ascórbico. Anais Da Escola Superior De Agricultura Luiz De Queiroz, 7, 115-130. https://doi.org/10.1590/S0071-12761950000100016
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