Highly selective visual monitoring of hazardous fluoride ion in aqueous media using thiobarbituric-capped gold nanoparticles

• First report on fluoride detection using 2-thiobarbituric-capped Au nanoparticles.
• A sensitive detection of fluoride using TBA-capped Au NPs is developed.
• Fluoride interface with TBA-capped Au NPs confirmed by Raman and FTIR spectroscopy.
• TBA-capped Au NPs as an optical probe detect fluoride ion in 40 sec.
• The probe is selective towards the visual detection of fluoride ion.

The rapid, selective and sensitive measurement and monitoring of hazardous materials as analytes are the central themes in the development of any successful analytical technique. With this aim, we have synthesized the thiobarbituric-capped gold nanoparticles (TBA-capped Au NPs) involving chemical reduction of HAuCl4 using 2-thiobarbituric acid (TBA) as a reducing and capping agent. The morphology of the TBA-capped Au NPs was confirmed using transmission electron microscope images. For the first time this article reports that the developed TAB-capped Au NPs displays selective, ultrafast and sensitive colorimetric detection of fluoride ion in aqueous samples. The detection of fluoride ion was confirmed by the disappearance of the localized surface plasmon resonance (LSPR) band at 554 nm using UV-vis spectroscopy. The interaction of F−F− with TBA-capped Au NPs in aqueous solution has also been confirmed by Raman and FTIR spectroscopy. One of the most exciting accomplishments is the visual detection limit for fluoride ion has been found to be 10 mM at commonly acceptable water pH range 7–8. The whole detection procedure takes not more than 40 s with excellent selectivity providing sample throughput of more than 60 per hour.

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