Dimethoate detection through a fluorescent coumarin dye

• Fast hydrolysis of dimethoate enables detection using coumarin fluorescent dye. • No interferences, excellent linear range (7.8–292 μg/L) and low LOD (3.2 μg/L). • Detection of dimethoate in green tea, with a recovery of 95.4 % (SD = 5.7 %). • Sensing mechanism exploits twisted intramolecular charge transfer. In this study, we present a straightforward and innovative approach utilizing a coumarin fluorescent dye for the detection of dimethoate in green tea. Initially, the pesticide undergoes hydrolysis in a NaOH solution, yielding our target analyte, methylamine. Following neutralization to pH 9, methylamine reacts with the dye in CH 3 CN for 20 min. After a careful optimization, we achieved an outstanding linear correlation (R 2 = 0.999) for dimethoate, spanning concentrations from 7.8 to 292 µg/L and LOD of 3.2 µg/L. Moreover, we successfully detected dimethoate in green tea, with a recovery of 95.4% (σ = 5.7%). Organophosphates pesticides (OPs), which dimethoate is one of the most used, pose a significant threat due to their toxicity upon both high direct exposure and prolonged low-level exposure, which has been linked to cancer. Therefore, the development of a detection method that is both selective and sensitive is imperative for safeguarding both the population and the environment. This method effectively addresses the stability challenges encountered by enzyme-based fluorescent sensors, thereby opening new avenues for the detection of organophosphate pesticides.