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Chemistry In Pictures

Chemistry in Pictures: Spotting high fluoride

by Manny I. Fox Morone
March 29, 2022


A series of six beakers containing liquids with colors ranging from yellow to pink. Each beaker has a label on it showing the decreasing concentration of fluoride in each.
Credit: Kaleigh Beale

Kaleigh Beale remembers when she was in elementary school in Virginia near the Chesapeake Bay some of her classmates had brown stains on their teeth. She was told the stains were a result of too much fluoride in the water. Fluoride is added to most people’s water in the US to prevent tooth decay, but excess fluoride can cause those brown spots or even brittle, crackable teeth. At higher levels, a person’s bones can become dangerously brittle, too. Luckily, there are ways to test for unsafe fluoride levels in water, like this method that Beale, a senior at Longwood University, is researching under the guidance of Sarah Porter. Beale came across the idea for this method in a paper from 1958 (Anal. Chem., DOI: 10.1021/ac60144a050), which describes a way to use a zirconium salt and a dye to sense fluoride in solution. Changes in the color of the zirconium-dye complex can detect variations in fluoride concentration in the parts-per-million (ppm) range, which is necessary to make sure the fluoride levels are under the World Health Organization’s safety standard of 1.5 ppm. What’s more, the approach could be a boon because it’s much cheaper than the usual method of fluoride sensing.

Submitted by Kaleigh Beale

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