Smartphone-assisted carbon dots fluorescent sensing platform for visual detection of Thiophanate-methyl in fruits and vegetables

Trimesic acid and o-phenylenediamine (OPD) were employed as precursors to synthesize yellow-green fluorescent carbon dots (Y -G -CDs) by solvothermal synthesis for the sensitive detection of Thiophanate-methyl (TM) in real agricultural products. The Y -G -CDs probe could specifically recognize the TM primarily through pi-pi stacking. Moreover, the fluorescence quenching of the probe was ultimately dominated by the PET effect, based on the interaction between the abundant carboxyl groups on the surface of the Y -G -CDs and the amino group of TM. A strong linear relationship between the fluorescence quenching of the probe and TM concentration in the range of 0-10 mu mol/L was observed and the limit of detection (LOD) was calculated to be 50.7 nmol/L. Compared to the interference pesticides, the Y -G -CDs probe demonstrated exceptional selectivity toward TM, with satisfactory recoveries of 96.3 % - 104.2 % in spiked food samples. The Y -G -CDs probe enables simple pretreatment, costeffective, and on -site detection of TM in fruits and vegetables with visual detection of the TM employing a smartphone-assisted sensing platform.