Portable sensor for the detection of picric acid using fluorescent carbon dot embedded PVA film

The current work emphasizes the development of a carbon dot incorporated portable polymer film for the sensitive and selective detection of picric acid (PA) in aqueous solutions. Nitrogen doped fluorescent carbon dots (WCD) were synthesized from white curcumin <i>via</i> hydrothermal method and characterized using HRTEM, FTIR, XRD, Raman and XPS. This promising scaffold can detect picric acid (PA) <i>via</i> fluorescence quenching, in nanomolar range, with a limit of detection (LOD) of 4.55 ppb (19.9 nM), demonstrating sensitivity far below the permissible limit of 0.5 ppm in drinking water. The quenching mechanism is rationalized by a cumulative effect of the inner filter effect and other secondary interactions. Successful incorporation of WCD into the polymer polyvinyl alcohol (PVA) matrix resulted in a fluorescent WCD/PVA film, and acts as a promising candidate for portable, real-time environmental sensing applications. The fluorescence studies on the WCD/PVA film affirm its practicability for on-site sensing by exhibiting fluorescence quenching in 25 nM PA solution which is near to the LOD of WCD solution.