Simplified sample preparation for fluoride determination in biological material

Abstract

A simple and rapid preparation method for the determination of fluoride in biological materials (blood and food) of various origins, is described. A homogenized sample was placed in a plastic diffusion cell and calcium phosphate added, it was then dried at 55 °C and treated with 70% HClO₄ and 40% AgClO₄. After digestion for 24 h at 55 °C, the fluorides released were fixed on the upper part of a diffusion cell containing a thin layer of NaOH. The analyses of the diffused fluoride were carried out with an ion-selective electrode. The proposed microdiffusion method, without mineralization, enables quantitative separation of the fluoride from the biological samples.