Molecular sensors for detecting fluoride, cyanide
doi:10.1038/nindia.2017.132 Published online 25 October 2017
Researchers have synthesized sensitive sensors that can detect minute traces of fluoride and cyanide in environmental samples including drinking water1.
Excess levels of fluoride ions in drinking water can cause dental and skeletal deformities while fluoride deficiency causes osteoporosis. Cyanide ions at low concentrations are harmful to human health. Existing techniques for detecting these ions are complex and expensive.
To devise a simple and cost-effective method for sensing these ions, scientists from the Sambalpur University and National Institute of Science and Technology, Odisha in India, led by Satya Narayan Sahu, synthesized two sensors by using specific organic compounds. They then explored their potential to measure the levels of fluoride and cyanide ions in aqueous solutions and tap water.
One of the sensors changed from colourless to deep red only in the presence of fluoride ions. The same sensor showed no colour change when exposed to ions such as chloride, bromide and iodide.
The other sensor changed from colourless to deep yellow only in the presence of cyanide ions while it exhibited no colour change in the presence of chloride, bromide and iodide ions.
The sensor that selectively detected cyanide ions in aqueous solution was also able to detect the same ions in tap water at low concentrations.
In the future, these sensors could be used to develop molecular diagnostic tools for selective detection of fluoride and cyanide ions in a mix of various ions and chemicals, says Sahu.
1. Padhan, S. K. et al. Optical discrimination of fluoride and cyanide ions by coumarin-salicylidene based chromofluorescent probes in organic and aqueous medium. Sensor. Actuator. B. Chem. (2017) doi: 10.1016/j.snb.2017.08.133