A Simple and Sensitive Fluorescence Method for Fluoride Determination in Dietary Supplements, Fluorinated Salts, and Tea

Fluoride at low concentrations is vitally important for human health, although its slight overdosage can lead to some adverse effects in various organs. A fluorescence method for the analysis of fluoride in different foodstuff has been proposed. It is based on the formation of the mixed-ligand complex of Zr(ІV) with Morin and fluoride. In general, the fluorescence of the complex shows a rise at 510 nm, as the concentration of the fluoride in solution grows. The detection limit and the range of linearity were found to be 0.1 μmol L, and 0.3–10 μmol L, respectively. This method was applied to analyze dietary supplements, іodized-fluorinated salts, and various teas, such as green, black, white, granulated ones, and tea in bags. The effect of brewing time, repeated brewing, and packaging materials on the concentration of the fluoride in tea infusions has been investigated. The new method proved to be very simple, sensitive, reproducible, accurate, and reliable. Moreover, this method has a powerful potential for the determination of fluoride in other food samples.