Research Highlights

Fluoride and cyanide in red

doi:10.1038/nindia.2010.32 Published online 18 March 2010

Novel sensors can now detect fluoride and cyanide in aqueous as well as organic environment by tracking colour changes.

Researchers have made two types of sensors using urea and thiourea and several organic compounds (nitrophenyl group as signaling unit and diphenyl ether/methane).

They tested the sensors by adding negatively charged (anions) fluoride and cyanide ions in the presence of other anions such as chloride, bromide and iodide. Urea-based sensors could not produce any significant colour change. But, the thiourea-based sensors turned pale yellow to intense red. Their colour remained unchanged even after the addition of chloride, bromide and iodide ions.

"If fluoride is present in any environment, it (organic or aqueous) will be detected immediately by this sensor but in the absence of cyanide," says lead researcher Mahabir Parshad Kaushik.

The authors of this work are from: Process Technology Development Division, Defence R&D Establishment, Jhansi Road, Gwalior and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India.


  1. Kumar, V. et al. Thiourea based novel chromogenic sensor for selective detection of fluoride and cyanide anions in organic and aqueous media. Anal. Chim. Acta. 663, 77-84 (2010) | Article | PubMed |