Natural deep eutectic solvent-assisted preparation of nitrogen-doped carbon dots for ratiometric determination of pirimicarb and pH

A novel green pH-sensitive fluorescent probe based on the surface passivation was designed for sensitive, rapid and reliable detection of pirimicarb (PRC). Using natural deep eutectic solvent (NADES) as the green precursor, N-CDs were hydrothermally synthesized, and combined with rhodamine B (RhB) to display strong fluorescence emission peaks at 400 and 582 nm, respectively. Upon the addition of PRC, the fluorescence sensor resulted in the enhanced fluorescence at 400 nm, while the orange signals hardly changed. Moreover, under the optimal conditions, the proposed assay exhibited super-fast, high selectivity and sensitivity for PRC with a wide linear range from 0.5 to 200 μg mL −1 and the relatively low detection limit around 0.3 μg mL −1 . Importantly, real sample analyses demonstrated that the as-presented sensor had excellent potential in pesticide monitoring. Meanwhile, the enhanced photoluminescence that become emissive upon stability from N-CDs was attributed to the reduction of surface defects after the surface passivation. In virtue of superior biocompatibility, excellent optical properties and low toxicity, the N-CDs were further employed to monitor the pH value.