Researcher develops colour-changing fluoride sensor

’The US Environmental Protection Agency recommends that one part per million (ppm) of fluoride ions is acceptable in drinking water, but above 2ppm is considered a serious health risk,’ said Sourav Saha, an assistant professor in FSU’s Department of Chemistry and Biochemistry.

’Because fluoride is carcinogenic, even at such small doses, a sensor is needed to detect fluoride selectively at very low concentrations and in the presence of other naturally occurring and biologically important ions.’

Working with a team of graduate students and postdoctoral researchers, Saha was able to develop just such a sensor. His research team discovered that a compound called naphthalene diimide (NDI) interacts with fluoride ions in a uniquely colourful way.

’NDIs are a family of neutral (albeit electron-deficient) aromatic compounds that are colourless until fluoride is added,’ Saha said. ’A small amount of fluoride will quickly turn the sample orange, while a larger amount will turn it pink. In this manner, it becomes very easy to determine not only the presence of fluoride in water, but at what levels.’