Fluorescent carbon nanodots for optical detection of fluoride ion in aqueous media

•An aqueous fluorometric nanosensor is designed for fluoride.•The detection limit is below the standard value suggested by EPA.•The level of fluoride in toothpaste as a real sample was measured successfully.•The analysis time is very short and the working procedure is very simple. In this work, a nanoprobe for sensing fluoride ion in aqueous solution has been introduced. The operation of this system is based on the quenching of the fluorescence signal of carbon nanodots (CDs) with a simple organic receptor. The linear trend in fluorescence signal with respect to fluoride concentration proved that Stern-Volmer equation was adapted successfully to the system with a linear range of 0–26.7mM and LOD value of 1.1×10−4M. This system showed to be nonresponsive toward weak basic anions except for fluoride. Using toothpaste as a real sample, the level of fluoride was successfully measured by this method.