Aplicaciones analíticas de la reacción entre el azul Nilo y el anión hipofosfito. Determinación cinética de poladío y oro

Authors

  • M. Hernández Cordoba
  • C. Sánchez Pedreño
  • P. Viñas López-Pelegrín

Abstract

In a 0.75 M sulphuric acid médium, the oxazinic dyestuff Nile Blue (C.L 51180) is not reduced by HzPO; (0,1 M) at appreciable rate. Palla used for the kinetic determination of the metalHc ion (0.30-2.50 p.p.m.). The reaction is followed spectrophotomietrically measuring the decrease of the absorbance due to Nile Blue at 640 nm. Variables that influence the heterogeneous catalytic process and the effect of some foreign ions are studied. As a consequence a new kinetic method for Au(III) determination is also presented. It is based on the apparition of an induction period in the reaction between Nile Blue and hypophosphite catalysed by Pd(II). The length of the induction period is proportional to the Au(III) concentration in the 0.40-2.00 p.p.m. range. In the prssence of a fixed amount of Au(III) the method is applicable for the kinetic determination of Pd{II) (0.20-2.50 p.p.m.) because 'the length of the induction period decreases wben increases the Pd/Au ratio.

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