Facile synthesis of fluorescent sulfur quantum dots for selective detection of p-nitrophenol in water samples

P-nitrophenol (p-NP) is widely present in soil and water environment, which brings great harm to the ecosystem. Therefore, it is of great significance to establish a rapid, sensitive, and selective method for detecting p-NP. In this work, fluorescent sulfur quantum dots (SQDs) were synthesized using a simple top-down approach. The prepared SQDs are monodisperse, uniformly distributed, and the size is about 2.9 nm. After adding p-NP, due to the internal filtering effect (IFE) between p-NP and SQDs, the fluorescence of SQDs can be effectively quenched. It is worth noting that the fluorescence quenching efficiency of the SQDs sensor shows an excellent linear relationship when the concentration of p-NP is 0.2–30 µM and 30–90 µM, respectively. The detection limit is 70 nM, which is better than other reported fluorescence sensing methods. The proposed method has been successfully applied to the detection of p-NP in water samples. Excellent recoveries of 90.9 ~ 102.0% and relative standard deviations (RSDs) of 0.33 ~ 1.66% were obtained, respectively, which confirmed the great potential of SQDs in the actual measurement of p-NP in environmental samples.