Fluorescence Probe for Detection of Malathion Using Sulfur Quantum Dots@Graphitic-Carbon Nitride Nanocomposite

A novel fluorescence-based sensor has been developed for the sensitive detection of malathion, an organophosphorus pesticide, using sulfur-doped quantum dots (SQDs) embedded within graphitic carbon nitride (g-C₃N₄) nanosheets. The SQDs were synthesized through a hydrothermal method, whereas the g-C₃N₄ nanosheets were produced via an exfoliation process. The resulting SQDs@g-C₃N₄ nanocomposite demonstrated outstanding performance for malathion detection in food samples, exhibiting a wide linear detection range of 10–120 μM and an exceptionally low detection limit of 0.02 μM. This sensitivity allows for accurate and rapid pesticide monitoring at trace levels. The sensor's performance was optimized by varying experimental conditions, ensuring that it provided high sensitivity, excellent stability, and impressive selectivity toward malathion, even in complex food matrices.