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Potentiometric titrations of selenium with a fluoride-selective electrode

1979; Elsevier BV; Volume: 111; Linguagem: Inglês

10.1016/s0003-2670(01)93249-0

1873-4324

José Bernal, E. Barrado, Rafael Pardo,

Chemical and Physical Properties in Aqueous Solutions

Selenite can be determined with a fluoride-selective electrode by two methods: a direct procedure based on the joint titration of selenite and standard fluoride with lanthanum and an indirect method based on precipitation of selenite with excess of lanthanum followed by back-titration with fluoride. In the first case the end-point is located by the second derivative method, and in the second case by means of a Gran plot. Direct titrations are suitable for selenite concentrations above 5 mM; indirect titrations are useful for concentrations as low as 0.5 mM.