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Highlights in Chemical Technology

Chemical technology news from across RSC Publishing.



Fluoride detection with the naked eye


07 February 2006

An effective sensor for the visual detection of fluoride in water has been developed by chemists in China.

Detecting fluoride

Chun-ying Duan, Zhi-ping Bai and colleagues at the State Key Laboratory of Coordination Chemistry in Nanjing have made a ruthenium compound that changes colour from orange to blue-violet when it bonds to a fluoride anion.

The system contains a photoactive ruthenium bipyridine segment that enhances bonding to the fluoride anion through electrostatic interactions. This provides the dramatic colour change that can be observed by a naked eye.

There is a growing market for simple and affordable fluoride detection systems. Fluoride has an established role in preventing tooth decay and is currently being explored as a treatment for osteoporosis. However, overexposure can also lead to fluorosis, a type of fluoride toxicity that can lead to pitting of tooth enamel and discolouration and is rare in the UK. Until now, there have been no compounds that provide a measurable output when they bind to fluoride anions.

The sensor can be prepared as a test-paper, similar to pH paper, and no spectroscopic instrumentation is required. It is highly selective and can detect fluoride in aqueous solutions at a lower limit of about 10 ppm.

"Until now, there have been no compounds that provide a measurable output when they bind to fluoride anions."

Duan and Bai hope that this cheap and effective new sensor will prove advantageous in helping to prevent fluorosis in undeveloped regions.

Ruth Needham

References

Z H Lin, S I Ou, C Y Duan, B G Zhang and Z P Bai, Chem. Commun., 2006, 624-626 (DOI: 10.1039/b514337c)