2,4,6-Trinitrophenol detection by a new portable sensing gadget using carbon dots as a fluorescent probe.

An optical sensing gadget using fluorescence of carbon dots (CDs) was developed to realize the in-field detection of 2,4,6-trinitrophenol (TNP) in tap water and lake water samples. Fluorescent CDs were prepared through a one-step hydrothermal synthetic route. The fluorescence spectra demonstrated that the CDs could specifically discriminate TNP from other nitroaromatic explosives in an aqueous medium. The fluorescence of the CDs was quenched linearly with the concentration of TNP in the range from 1 to 100 μM, with a detection limit of 0.48 μM (3σ/k). The detection mechanism was ascribed to the synergistic effect of the inner filter effect and electron transfer. In addition, a portable sensing gadget based on a high-precision RGB color sensor and a micro control unit was developed. With use of the sensing gadget and the CDs, TNP detection in tap water and lake water samples was realized. Importantly, the portable sensing gadget combined with highly stable, low-toxicity, and sensitive CDs might have great potential for application in extensive in-field sensing situations. Graphical abstract Carbon dots synthesized with 4-(diethylamino)salicylaldehyde as the initial material were used for 2,4,6-trinitrophenol (TNP) detection. TNP quenches the fluorescence of carbon dots, and the mechanism is ascribed to the synergistic effect of the inner filter effect and electron transfer. A portable sensing gadget based on a 32-bit micro control unit was successfully applied for in-field TNP detection.